They’re still different careers, not “levels” or whatever.

A phd scientist may not be a good fit for an engineering job. Their degree doesn’t matter.

An phd-having engineer might not be a good fit for a research job either… because it’s a different job.

researchers are paid 2x what engineers are paid at OAI, even if it's not the same job there's still one that is "higher level" than the other.

In terms of pay at OAI, sure.

But being an engineer isn’t just a lesser form of being a researcher.

It’s not a “level” in that sense. Like OAI isn’t going to fire an engineer and replace them with a researcher.

Well I am an engineer but I have no problems in buying that in case of forefront tech like AI where things are largely algorithmically exploratory, researchers with PHDs will be considered 'higher' than regular software devs. I have seen similar things happen in chip startups in olden days where relative importance of professional is decided by the nature of problem being solved. but sure to ack your point its just a different job, though the phd may be needed more at this stage of business. one way to gauge relative importance is if the budget were to go down 20% temporarily for a few quarters, which jobs would suffer most loss with least impact to business plan.