People just assume older code works. I'm regularly finding stuff we've had in production for months that never did what it was supposed to. You could go back an

People just assume older code works. I'm regularly finding stuff we've had in production for months that never did what it was supposed to. You could go back and write all the same tests after the code is done, but I find it extremely unlikely that anyone will actually reach the same degree of test coverage (I know I for one never have). And even if you're one of the rare few who will pay down this technical debt eventually, it takes away quite a bit of the value of the tests to muddle through all the coding work without them.