Credits, where credit is due

I’ve been really enjoying the Canadian series Letterkenny. It is basically a comedy showing the misadventures and interactions of a few small-town groups - hicks, skids and hockey players. The focus is usually on perhaps eight characters. Another dozen characters are also pretty prominent with appearances in many episodes and are sometimes major characters for an episode or two. The best feature of the show is the clever writing by Jonathan Torrens.

My question is the credits. The show was developed by two of the main characters, one of whom also directs well. The credits give major billing to these two and to the other six prominent characters, followed by direction, production, writing. Then they list all the “minor roles” at once for a second or so. This list often includes some fairly prominent characters. Often, impressed by a performance, one has to pause at this list.

Given that show business does not seem to lack egotistical characters, I wonder if there are (union) rules for screen time vs. credit? Perhaps no one much cares? FWIW this is a show made for CraveTV, a Canadian “Hulu” wannabe.

I found a SAG page on this.
https://www.backstage.com/magazine/article/negotiating-sag-mandated-billing-34302/

It basically says that while some credit is required for casts of under 50, the size and placement must be negotiated by your agent or manager.
Now not all productions are SAG, and I suspect lots of Canadian productions aren’t SAG.
What is regulated is the distinction between a featured player and an extra. Neither may get credit, but non-union extras don’t get treated as well as featured players on set.
When my daughter was in a SAG show, she got billing with one other actor during the opening credits. This was the third season, and this type of billing was already established. Plenty good for us, so we never thought of trying to negotiate anything different.

Every time someone comments about how long credits are these days, I make up a story about a crusade in the Sixties led by the Professor and Mary Ann.