Between needing to be able to service warranties on new cars and parts commonality across different models, it makes sense for a manufacturer to contract their suppliers to continue to produce parts outside what’s needed for initial production (to a point).

After all, if a warranty outlier or defect develops down the road, it’s a lot more expensive to reinstall old tooling and restart production than to just have extra parts on hand.

The aftermarket also plays some role, especially when you get into vehicles with longer service life applications (trucks, emergency vehicles, taxis, etc.)