I work at a development firm that mostly services local corporations, and the average time we have to maintain the software we build is fairly low. My boss and I both appreciate the TDD philosophy, but when client budget constraints are what they are, TDD is one of the first things to go out the window. Our CEO has (understandably) a hard time selling a project for 20% more money when the client won't get 20% more features. Additionally, if/when bugs come up, we're able to sell support and enhancement sprints. So really, TDD would reduce the (already small) revenue stream we get from support, at the benefit of being "one of the cool kids".