If you have experience working in industries unrelated to software engineering, could you describe how does the hiring process look like for regular and senior professionals?

I'm curious to know if endless rounds of interviews, take-home assignments, multi-month timelines, the need to prove you know the absolute basics after working in the field for decades, and extremely high chances of rejection are the norm anywhere else.

I've hired many people for science and automation software positions at small and large US biotechs. We usually did a phone screen (both technical and HR), then an on-site interview. The overall process wasn't much different for Ph.D. vs. Bachelors/Masters, but of course we asked very different questions depending on the level. Ph.D.-level positions were usually required to give a brief talk (partly to probe their communication skills.)

For certain specific software automation positions, we did end up giving a coding test during the on-site interview. But no homework or multi-round stuff.

The present situation in software is mostly the result of an oversupply of labor. Companies are endlessly picky because they can be. I am old enough to remember other recessions where companies could make ridiculous demands (once had a company demand I come in early Sunday morning for an interview, just to make sure I was truly committed to working 24/7. No thanks!)

Recessions eventually end, although not always in a way that helps specific careers. Good luck!

Lower paying jobs tend to be a single in person interview. Some jobs have a phone interview and then an in-person. Some jobs have practical tests during the interview, such as with welding.

You go in, have a chat to the manager or hiring manager involved. They think you're "nice" and you're in.

Many years ago some tech roles in non-tech companies worked like this too.