Since you talk about fuel filters, an interesting fact on 1st gen BMW Minis (2001 to 2006): the very first models, up to 03/2002 had an enclosed fuel filter, which was costly to replace. After that, it was changed to a design with a replaceable fuel filter (so the same $15 or so part cost).

The fuel filter is inside the gas tank, but replacing it only involves removing the rear seat (which is easy) to have access to a cap under which the fuel filter lives.

I'm actually planning to tackle that in a few weeks, it looks like a medium-difficulty DIY, with some pitfalls that could make the car not start afterwards if the seal is bad.

Edit: fortunately the awesome ModMini has a video showing how to do just that: https://www.youtube.com/watch?v=rCppUQfNZQQ

On an unrelated note, another design change on more recent vehicles I've seen is to fuse the wheel hub and wheel bearing in a single part. You go from a $50 wheel hub and $20 wheel bearing (approximately) to a $200 assembly. While replacing the hub automatically involves replacing the bearing, the reverse is not true, and bearings are a wear part, which WILL have to be replaced eventually.