I am interested to know which industry fielding mechanical engineers would have the least regulatory oversight.

The university I attended was very heavy on theory and taught absolutely nothing with regard to laws, rules, standards, etc. It makes sense that this would not be taught from a science standpoint because I am finding many standards have errors and are born of misperceptions. Laws are even worse in that they are so influenced by politics. An inspector can come on a job, spout some nonsense, and hold up the schedule until we pour through thousands of pages of rules and regulations to prove them wrong. The worst is when the requirement is totally made up, they can't cite the source, but retain the power cost us time and money. Once proven wrong, there seems to be no way to hold them accountable for losses.

I've been in engineering for 15 years, licensed for 9, and frankly, I am tired of playing discount lawyer to fight incompetent regulatory inspectors who like to play discount engineer.

Can anyone recommend an industry where an engineer can focus on engineering or do I need to get out all together?

I used to count sand. Now I don't count at all.