Many don't though. Typically, though, the place to add no-color is even on the same line as this test and is a very cheap add, so anyone looking to add it would do well to consider adding both.
There's a bunch even on that list. I had a look at ffind, the second on the page and found nothing to test if the output was tty or otherwise.
Generally though, I'm not out to point fingers, it's just a fact that not all software is complete and bug-free. We're all people with limited time and we don't have the attention to detail that dealing with the maliciously compliant children that computers are takes.