> there are other considerations besides one measure of efficiency

Bruh that's literally what I was saying? Instead of how efficiently can you replace a filter in an engine, another benefit might exist instead. Said another way, maybe the "juice" gained from redesigning a fuel filter system instead of using an existing one form another car wasn't worth the "squeeze" of cost and development for the company.

Kinda feels like maybe you (the majority of replies to my original message) didn't get the point, and instead took this as some literal suggestion that I think engines need to have filters in certain spots.

The fact that so many people took this as literally as they did, and seemingly chose to ignore the underlying message of "hey maybe consider tradeoffs exist" makes me start to worry about you too.

No, you were saying that accessibility is subservient to efficiency.

And you were explicitly told several times that your hypothetical efficiency just does not exist. So constantly saying, "Yeah, but what if" looks like you're being obstinate for its own sake.

If the majority of people "didn't get your point", consider that maybe you aren't great at getting your point across.