> literally no reason for a new model to drop

You're making an extremely bold hypothesis that your internet armchair knowledge about what investment auto manufacturers make in research, design, and marketing to remain competitive in the marketplace of car sales easily exceeds what auto manufacturers know about that same topic.

You would need some strong supporting evidence to convince people of that. One would be any 6+ year old model of vehicles that sells as well as or better than any 5 year old or newer model of vehicles, even if it only competes on price. Can you name such a model? What share of the U.S. car sales goes to that model? What is their profit margin, and how to does it compare to models that Toyota sells?