But some banks (Starling in the UK) seemed to be able to work around that and have a decent CI/CD story, and as you say - it doesn't usually make the software any better, just adds bureaucracy.
The only people who I have met who turn the interview process into a gamut of algorithm puzzles, are people who happen to be very good at them. These also don't tend to be the people running things at banks, let alone large ones.
The problem with "artisanal developers" is that they tend to overestimate their proximity and underestimate how much of a "system" they actually should build. Most of the time they lack domain knowledge, too.
If you can identify the cross-cutting interactions that will result in the biggest risk for the project, and put how to handle those in a design that is communicated well, you can leave freedom how to do the rest and the craftsmen will be appeased. But that needs a good deal of domain (and people) knowlege.
I also think it depends on how you define quality. In terms of medical my qualification criteria is based around a 0 deaths or 0 failure rate over a lifetime, not so much what it was build with. Some people would likely disagree with that.
But for who gets in the door for implementation work, it's still tech conversations and a bit of "who you know" that count over qualifications and hard tests, in my experience.
As someone that's worked around banking and finance a fair amount in the last few years, I'd say this is not universally true. I've never worked in the medical sphere, but I have worked on everything from tiny payment systems at SMEs to massive compute systems at banks in the top handful of the fortune 500, to quasi-governmental inter-bank communications bodies, and really I've not seen any more focus on qualifications, nor reliance on 'hard' coding interviews than I've seen elsewhere in software.
Maybe medical is different, AFAICT finance and banking ain't.