I can’t tell you how many interviews I’ve been in where the interviewer was clearly not technical but asked questions around your technical background.

That's just crazy town, I can't imagine doing that. I manage software engineers, and I did real time control software for a couple decades before I became a manager. Here's roughly my process:

• I get the matching resumes from HR - I try not to ask them to assess anything besides degree and very rough background.
• I read through all the resumes I get looking for qualifications and red flags.
• For the top three to six, I'll set up a phone interview with me and our top technical person. But the questions there aren't especially technical, they're mostly to get the person talking, look for motivations and interests, make sure we understand the things on the resume, see how they communicate, and get a sense of how they'd mesh with the team. It's also to answer every question they have as honestly and candidly as we can; I'd much rather find out that we're not a good fit in a phone interview than later.
• For any that do well on the phone screen and are still interested, I'll set up in person interviews with one or two groups of my team. I make sure it includes people who have been here for decades, people who are mid career, and people who have only been here a couple years. I do that in part because I think they look for different things in the candidate, and partly so the candidate can get different perspectives on our work environment. I try not to have more than three of our people in an interview so it doesn't feel like an inquisition. I'll talk with the candidate for 30 minutes when they come in to let them know what to expect and to make sure they take the opportunity to ask questions, and then afterwards me and the top technical person will meet to see how it went, if there are any other questions, and to get our in-person sense of the candidate.

Then that's, no other interviews in the vast majority of cases; I get feedback from the team and then make my best call. If none are good fits, I'll repeat the whole process.