Yes, the executive is allowed to decide how the laws are executed. And in the event that such laws are ambiguous, the courts are supposed to make a judgement on

Yes, the executive is allowed to decide how the laws are executed. And in the event that such laws are ambiguous, the courts are supposed to make a judgement on what the law is. If you default to just deferring to the interpretation of the executive, why have a legislative branch at all? Why not just pass a law that says "regulate all the things"? Our government is intentionally limited. It may only do the things it has been explicitly granted the power to do. When whether that power has been granted is ambiguous, that is something that needs actual judgement on. We should not have a default to the government's own interpretation. We certainly don't (try to) default to the courts just assuming whatever the police say the law is when it's ambiguous is what the law is. Why should we do that for other regulations?