I mean, you do incur a cost for programming with TDD though. The benefits may repay the cost in the end, but the cost is still there. And for that matter cars do undergo destructive testing, just not TDD--and the problem there is presumably that the car benefits from taking a holistic component-driven approach, "here is what I want the car overall to look like, and what components I want to fit into the space inside, now how can I reduce the rollover risk?" rather than "here are some basic expectations of a car, I expect it to be able to move forward and hold a passenger, let's make the smallest thing which causes that to happen. OK now let's add a single passenger, and let's test that bugs aren't flying into your face at highway speeds so that we remember to add a windshield eventually. (1000 steps later) Crap now we're testing the ability to shift into reverse and none of my homespun bare-minimum engine design is going to work there."

TDD probably pays its best rewards with relatively simple well-defined projects, and needs to be deployed with a modularization strategy. Possibly the wishful-thinking strategy of top-down design would be a natural complement, since when you wishfully think of a function you can hopefully quickly write a test or two for it.