I do know about this stuff (currently work for one OEM and have worked for 2 others) and you're exactly right.

Something that hasn't even been mentioned is all the meetings, documentation, coordination between people that work on the components that have to interface with each other. That labor is significantly reduced when you offload most of that to the touch screen because some of that interface can now be done by the same person without any meetings. That's not just cost savings, it's also time savings, which is part of why Tesla was able to bring the model 3 to market so fast (fast at least in the car world).

That said, I much prefer tactile controls. I recently moved from a BMW to a Volvo had the BMW had physical controls for most common functions while the Volvo only has a handful of buttons and one knob for volume. It's a pretty good balance, but I do miss a few buttons and more could be done on the touchscreen to ease that longing (such as customizable shortcuts).

Cadillac is starting to go back to more tactile controls because they've learned how terrible it is without any (my wife has a CTS so I completely understand why they're doing it -- it is awful). I hope Audi changes course too.