I've seen a couple out-of-memory deaths (mostly non-paginated db queries, but compounded with the inefficiency of py2), and occasionally an accidentally quadratic loop (which would be faster in C, but usually can just be made fast in Python with more thoughtful code), but it's almost always the DB—oops, I need to add an index, oops I did a cross join, oops, I'm spawning additional 10 queries for each row returned. The time spent in Python on a slow endpoint is usually negligible.

Dev: I get paid for writing features. I can write new features faster in {insert slow interpreted language here}.

Also if the company is of any size, whatever they write has to fit in the rest of their CI/CD stack and pass whatever kind of code review the company does or doesn't implement. So yea it's easy to say devs suck (and they do), but without looking at the entire process they are involved in it can be very hard to qualify why they suck and where the suckage comes from.