Ian F: I think you are dealing with the opposite problem. You are scaring them off.
PDF's are scary to residential contractors who frequently don't even use computers. You are intimidating them.
The bidding process is completely different for commercial and industrial construction than it is for residential. Commercial uses Means, and various unit pricing methods based on some factual system. Essentially, the project is well defined (by engineers, etc) beforehand, and then there is a "right" price. The differences become the markups, or special discounts identified for various components.
Residential contracting is a trust relationship. Honestly, the price is a bit of a guess. It has a lot to do with the customer and their expectations and attitude, not so much with the actual finished product or specs. Just as property owners are trying to identify a contractor they can trust to work fairly with them, contractors are trying to identify owners they can trust to work fairly with them also.
Many don't read plans well, can't bid projects accurately, and aren't that good at estimating time schedules. But the dynamic of what they deal with is completely different. They are asked to enter people's private homes, work around the kid's school schedules and the dog's eating patterns, and work with sometimes overly fussy people who don't really know what they want but saw something they liked on HGTV (although they fail to recognize that they REALLY can't afford the vision they have in their mind). Residential contractors are really just trying to make a living in a very unpredictable world.
They are completely different animals.