The @ doesn't work on my phone..
Jscott, I completely agree with your points and have that kind of relationship with many contractors. It was my plumbers taking Me to lunch, not the opposite. My regulars get consistent work from me, I refer them often, pay them on time, and don't beat them down on price like many investors. They really like me.
However, not all contractors "get it" because like you said most aren't good businessmen. Really most business people aren't very good at business, the failure statistics don't lie. Ive found through experience that some contractors have a negative view of investors. I think many investors are cheap, want to cut corners, beat the contractors down on price, try to add to the SOW without adding to the cost, and can be slow to pay. So if this has been their experience or what they've heard from other contractors they can hesitant, and I would be too. So if that has been their experience and they meet an investor who tries to hang that carrot out there they're going to be hesitant if not fully resistant to it. Again just my experience.
I've simply changed how I approach contractors and how I propose things to them, that's really what I was suggesting to the OP. A good contractor doesn't have to work with us, they can find other opportunities. A smart contractor sees the advantages that you listed in working with us, we don't need to oversell that to them.