Most of the populated areas of the country have laws, rules, ordinances, etc. such as the one being discussed that have been in place for a long time. Seems kinda odd to me that more of the members here aren't familiar with them since we're more likely to be the ones cited for violations, I for one have been cited in the past more than once and admit I currently violate several. Play the game, take the risk, get caught, pay the price. I've had several roles in the game.
Get a fine here and think you're not going to pay because you're mad that you didn't know the rules? They'll put it on your water bill and guess what happens if you still don't pay?
Writing laws, rules, ordinances, codes, or whatever you want to call them isn't easy because if you make them specific too many people will be in violation and if too lax you'll end up with neighbors fighting. So the rules are written vaguely to allow the code enforcement people to use their judgment. They can tell the difference between someone running a business and other people just doing work for themselves, friends, relatives, or as a hobby. That includes many other things besides automotive.
Most code enforcement departments have more potential "work" than than they could handle (if they went after every offender) because they have to take care of all kinds of things, not just automotive stuff. So they're not out actively looking for infractions EXCEPT in certain areas when there are extenuating circumstances that some one or a particular group consider as a justifiable reason to cite infractions in the area. A section where slum lords do as little maintenance as possibly for maximum return on investment while the area deteriorates would be an example if lets say a group of tenants puts in a complaint. Another example would be if the developer building the new homes in the other recent thread went to the proper gov. officials and asked that codes be enforced in the whole area where they're building the new more expensive homes.
It's very hard to write something that keeps people from running auto repair shops out of their home garage without keeping people who fix their own cars and hobbyists from being able to do what they want to do without creating a lot more work for government people to monitor whats going on. Not just automotive but other things as well. So, vague rules were written at some point which aren't enforced by actively trying to identify violators with code enforcement people given the power to make a decision when there's a complaint. Typically a complaint is only made when there's active gross violation of some type so if they show up most offenders aren't really surprised. Yes there are exceptions where one neighbor is mad at another or someone is trying to maximize the selling price of a nearby property but as a general rule of thumb the system works.
If you (members here in general) keep your yard, home, vehicles, etc. that can be seen from the street or by neighbors at or above the aesthetic level of the nicest neighbors properties it's very unlikely you'll get complaints unless you make a lot of noise or create unfavorable odors when most folks are home. Respect your neighbors, treat them as you'd like them to treat you. If you hear them having a kids birthday party on the other side of the fence it's probably not a good time to fire up a chain saw & log splitter even though that was your plan for the day, even though there's no rule against it. Maybe even go over and ask when the party will be over explaining what you'd planned and saying if it's till dark you'll just do it another day so you don't annoy them. Courtesy goes a looooong way over time.
Speaking of fences when I was in design school I had a class one semester dedicated to barriers. The professor's motto was "Good fences make good neighbors". If you're (forum members in general) gonna keep a bunch of crap in your yard most people wouldn't want to look at routinely, then do something so they don't have to look at it. A wall, fence, hedge, trees, topography changes, or whatever it takes so neighbors don't have to look at your crap on a regular basis goes a long way toward good relations with them for those of us who kinda disobey some rules. If you're putting up a fence consult them on opinions of type, style, color, etc. Same thing with plant materials or whatever. It lets them know you realize they have to look at it forever and are considerate. If two or more neighbors have differing opinions then have a neighborly meeting of the minds for a compromise. Takes you off the hook for putting up something that wasn't their first choice and they'll probably never complain about your crap even though they may know it's behind the fence and not allowed by zoning or other regulations. They're also less likely to complain if you do other things some might find a nuisance like say painting a car.
I have 6 vehicles and a 24" enclosed trailer on my 1/3 acre in a subdivision of single family homes with only one vehicle tagged, no complaints because you can't see most of the unregistered ones from road or neighbors and the one unregistered project I do have in the driveway always has a cover on it. Front yard is above average appearance compared with neighbors and no parts etc. can be seen from street. Car cover gets replaced before it's a tattered mess blowing around to keep up appearances. Yes I'm violating one or more local codes and if I got a notice from the city I'd still be grateful for the time I already got over the past 14 years.
I have a BS in City Planning, I've been a member of the city zoning board of appeals, I've been cited and paid fines, I've put in complaints, and I've talked to neighbors on a "you need to fix this situation or" type of basis as well as "I'm going to do .... and would like your opinion". I'm regularly in contact code enforcement people in my current city for various other reasons so I know the inside office people as well as outside personnel. The current code enforcement officer for my neighborhood is a car guy like us and knew who I was before he held the position because I used to work on his aunts Corvette so he stops by to see what I'm working on occasionally. I get no special treatment, and if a complaint gets put in about me I'll get cited. Currently pondering the best time to put my car trailer in my driveway for repairs because I know it'll take longer than trailers are allowed to be in the driveway. Rule is primarily to keep neighborhoods from being filled up with boats, jet skis, landscape trailers, etc. but my enclosed also falls under "Trailers". It's a good rule IMO even though it makes things a bit more difficult for me.
If you guys think the rules being discussed here get people fired up you should see what happens at city meetings when sometimes millions of dollars are involved.
To the OP, my suggestion would be to pay your fine, stop creating a disturbance with various media, stop contacting gov. officials, clean up your current violations, and "crawl back under the rock" so to speak while things blow over. Just let things quiet down a while, don't keep stirring the pot. They're not going to drastically change the rules because you think they should. If you keep irritating the neighbors and gov. people you're gonna become "that guy" which won't help you in any way, then eventually you'd need to move to do the things you'd like to do. Consider selling some of your "projects" and use the money freed up to screen off your property from public as well as neighbors view. Selling some or all the projects would be very liberating. They're a "weight" you may not realize you're carrying till they're gone. I've BTDT in the past. After a good while has gone by and you've put up visual barriers then consider what project to do. Good luck with whatever you do!