[Mister X]

I think you have to consider a few things. Staged of course is totally legal and no problem as far as I can see. If a girl is wearing one of those teeny tiny micro-skirts in public then I guess you could argue that it might have been her intent for something of the sort to happen but there is still the issue of a signed model release. Or in these cases the lack of one. I'm not exactly a legal expert but the way I understand it the only time you don't need a signed model release is when someone is in a crowd shot in a public place. A jumbotron is different because it's ephemeral and can't really be considered publication. And of course live events are different because it's quite impossible to get the permission of everyone that attends an event before it goes out on the airwaves.
The upskirt thing is quite similar to the beach candid situation. You can argue, and rightly so, that a girl wearing a bikini on a beach is intending to show off her assets. But the law has been quite clear that you still can't take her pic and publish it for personal gain. If you are a credentialled news photographer you can use her pic in crowdshots but if you intend to use pics of her individually you still need a release in some (most?) jurisdictions. And the fact that it's legal to take pictures of an actresses tits if she goes topless somewhere has no bearing on the issue because there are different legal standards in those cases.
Then in the case of both upskirts and beach pics there is the issue of the girl's age. That's a whole different can of worms. And they are big ugly worms.