My observation on this is that there are instructors that learned to
fly at large flight schools catering to teaching airline pilots. The
thing to remember is that these flight training schools are not
teaching these pilots to fly single pilot single engine airplanes.

Good point. I once checked out in a Piper Arrow a pilot who had been trained
at a place like that. He extended one notch of flaps before the landing gear,
because that's the way they do it in big airplanes. But it didn't make any
sense in the Arrow, as the max speed for gear extension is 150 mph, but for
flaps is only 125.