The OP also mentions Facebook and Spotify also are violating rules, and to my knowledge they're not paying apple "billions", so this explanation doesn't pass the sniff test. The actual reason is probably far more banal: these apps command a huge user base, which would be very upset if apple banned these apps. As a result apple is letting such infractions slide because they don't want to upset users.
The EU already handed Google the browser market on a silver platter, under the guise of “competition”. How much farther would they go if Apple prevented a perceived competitor from abusing users?
I think a more likely explanation is they know what would happen to their sales numbers if they kicked off Facebook and Spotify.
Why, so that developers can have absolutely no rules against abusing their users?
If you’re important enough Apple will let you get away with murder compared to normal devs. Users don’t buy phones without FB, Instagram, Spotify, WhatsApp, Google apps, etc.
There is only one time I remember anything happening to a big app. Fortnite probably could have tracked people for years. But the they took away Apple’s cut and publicly stuck a thumb in Apple’s eye at the same time. So they got booted.
That's part of why Facebook felt rightfully indignant when Apple moved to kneecap attribution and acted like it had never heard of it