I’ve been a software developer for over 35 years, since 1980. From Day One, it was understood that software must be tested. It’s common sense.
I’ve never met a colleague who didn’t believe testing was essential. I’m very curious where you are finding these programmers who don’t test. I’m utterly dumbfounded.
Now, whether they do a good job of testing is another question entirely. They may be very sloppy in this regard, but then, there is no shortage of bad programmers in our profession.