From seeing your posts, I think you have a psychologica lock that under mines your self-confidence.

I'm curious what type of company has these team demographics. Startup, agency, SMB, bigcorp, academia, or?

Everywhere.

5 years ago I was at a small bootstrapped startup and one of the worst engineers I've ever worked with was saying he'd expect to be a CTO of a mid-size startup in 5 years. He had just started his career. He managed to concoct quite an interesting fictional LinkedIn profile, while in reality he had almost no coding experience. He was a grifter.

In larger, established, tech companies this wasn't as prevalent but mostly because people were a bit more mature and respectful.

I guess it comes down to maturity. In startups and SMBs it was easy to find this attitude. Junior developers are often the most difficult.

Usually this kind of thing comes from “trying to keep costs down” at a poorly funded firm, usually startup-ish. I’ve worked places where the oldest engineer was 30 and it’s rough, quality and stability just aren’t in the average 25 year old’s toolkit.

If you need to knock someone down a peg or two, just get good at finding race conditions.

Webapp coding is harder than it appears because of them. I haven't worked in a codebase without them.

But they're usually so unlikely to happen it's not worth fixing them all because it can lead to very specific and tricky code. So as long as the consequences of it occurring aren't really bad, I just leave it alone.