Actually they sit in their offices and try to figure out how to make a profit, and it seems like opening windows must cost too much or weigh too much or some such reason. Over the years the technology of windows that open and can be adjusted to regulate airflow has died. We used to have vent windows in the front and back doors along with the larger windows that went up and down. Your Buick and several others had vent windows at the far rear side windows, too. Now, nothing.
Maybe it’s because air conditioning is standard equipment now? Maybe most people prefer to drive with the windows closed? Who knows. But over the years the complex adjustment of windows in cars has disappeared, with hardly a comment.
Some station wagons had rear doors with an unframed power window and two different handles, so you could open the door to the side or flop it down like a tailgate. That’s gone too. Now you get a hatch that rises up and hits you in the face. You can be sure that’s cheaper to manufacture, and lighter, too. Seems to be selling, though.
I guess the makers are telling you they are not interested in your problem.