If it is a part with a regular maintenance schedule, it should be designed for maintainability.

Most maintainability conflicts come from packaging and design for assembly.

Efficiency more often comes into conflict with durability, and sometimes safety.

This is like saying you can get a 10% improvement in battery life by changing where you position the RAM on your motherboard.

There is just no universe in which placing an oil filter in one location or another is going to make such a difference. You'd have to mount it completely outside the engine, say sitting as a cylinder on top of the hood, and even there you are not going to get a 2mpg improvement.

If the engine failed due to missing oil change because of the difficulty, the whole car is gone. The waste in cost, material, and environmental impact far outweighs the savings in 2mpg improvement.

We don't have magic oil filters which last even 22k miles. You should be replacing them every 6 months / 6k miles, or 12 months / 12k miles depending on your risk tolerance (some people suggest even half my short interval).

Anyone who actually drives their car regularly will be doing an oil change at least twice a year. If an oil change takes more than 30 minutes of actual labour time of an inexperienced mechanic, it's going to be a serious financial burden which will likely outweigh any 2mpg improvement.

I’m no mechanical engineer, but I would assume those extreme tradeoffs occur more often when repairability is not prioritized from early iterations. I.e. “boss we’re 90% into the design cycle why are you bringing up the position of the oil filter now?”

There’s definitely a programming equivalent as well…

Except..there is never such reason. They can put the filter anywhere in the pipeline. Some even have it exactly where it should be: https://www.ifixit.com/Guide/2013+Subaru+Legacy+Oil+and+Oil+...

Most cars sold in the US are not aerodynamic so it seems a couple of mpg isn't the focus anyway