I suspect this contractor is used to installing contractor grade material, and then, charging an arm and leg for a change order. The OP has to look at this stuff, from now until whenever, and has a right to pick whatever fixtures and grade of product she wants. If she's going to provide them, have them on site. If it's left up to the contractor, then establish a proper markup....Some contractors can't think past blow and go. If they can't do it with a nailgun, then they aren't going to do it.
You are right, there are talented contractors with good people skills, and there are even more mediocre contractors. And then there are really bad ones... truth is, a person being a contractor doesn't always tell you a lot about their skills or talent (or lack of).