I did not mean to imply that a CS degree would be necessary for all work in software. I would oppose such a system as obviously irrational and serving only a subset of incumbents. With your background, you would if anything have found it much easier to enter the field, as you would have known exactly what to study for and, once certified, had more bargaining power with specific employers.

Barriers to entry exist today, and will always exist in some form. The question is who gets to define them. I am arguing that the workers themselves should have more of a say than they do at present.

One union certification could literally be passing some randomly selected leetcode problems. Ideally, there would be a variety of certifications to reflect the variety of niches in software (someone doing TLA+ for embedded applications shouldn't need to know anything about web app architecture, necessarily).

The difference is that you wouldn't have to do it for every new employer, and workers would have more say in defining the body of knowledge considered relevant.

I don't think anyone would advocate for university credentials to be a hard requirement. I personally have no relevant university credentials except some math courses from a community college.

That said, I think it would be fine for someone to submit a transcript from a CS degree to be certified for basic algorithms knowledge in lieu of sitting an exam on that topic.

Depending on how it's implemented, it could actually work to the benefit of non-degree holders. A certification reflecting your ability to leetcode and a review of your portfolio, could put you in the same place as graduates of elite CS degree programs.