Not only does it happen all the time, it's often the only way to sort out what legislation means in practice.
A US-centric perspective, stereotypically, would be like 'my Starbucks coffee is too cold, I am suing'. You can have common law without sue-happy individuals.
No, the judges rule with what they have, based on the case’s specifics and the "legislator’s intent" underpinning existing law.
Although it does not become law, their ruling can be used as precedent in later similar cases, until the legislator catches up.
For people, yes. For businesses, absolutely not.
In the EU Apple could have sorted this out with regulators without having to involve lawsuits and legal proceedings.
Unfortunately Apple has a strong deeply held conviction about its walled garden which it’s unwilling to compromise on.
Tim Cook’s hundreds of millions in salary/bonus are dependent on Apple being able to extract a 30% cut out of the entire app and media ecosystem.
I'm certain they have the best legal team that money can buy, but I'm equally certain that that legal team is under the sort of pressure that happens when a multinational corporation is looking at the prospect of possibly losing billions of dollars in zero-effort recurring profit. I also think these sort of behaviors are damaging their brand, which is certainly Apple's most valuable asset - which is to say that I think they're acting in an irrational way, because of the amount of money at stake.
Apple will as shown here do their best to comply the least with the intent of the legislation, but it's up to the legislators if it is acceptable.
E.g., if notarization turns out to be used for central gate keeping by declining specific apps in the human review step or by using it to impede the process for apps intended for third-party stores, that would be a violation.
So there can be multiple layers to this, and ultimately I don't think the EU really works as a robust legal system any more, there are so many politically driven cases where the courts follow the politics not the law.