Yeah I get that the logic is different. The court decided based on the exact wording of the law, which they are changing last I heard. One worries about laws rushed into battle; but one worries more about the laws they spend time trying to pass. Good results are rare.
Laws have a serious need to catch up to the 21st century. A local case where involved a man who emailed pictures of his parts to a recipient who didn't want them. The police got involved and prosecuted under laws related to sending unsolicited porn without an envelope over the pictures marking them as adult content or some such thing that you have to do when you send unsolicited porn. The judge threw out the case on the grounds that email has no envelope so it simply didn't apply. The law had no concept or provision for what happened, and one could wonder why the police chose that route. But it didn't work. Obsolete law.
My pondering on the expectation of privacy is just that I would have none if I wore a kilt, for example. While I certainly would not expect upkilting, the only thing keeping it from happening is expectation of proper behavior on the part of other people. History shows counting on people to behave is not necessarily a good idea.
That's one of the reasons there are so many laws, after all: to encourage compliance and penalize the offenders. However in the case of a kilt or dress or skirt, this particular problem can be prevented entirely by choosing to wear a garment not vulnerable to such invasions.
Oh now I know this sounds too much like "her clothes = she asked for it" but I think that's a totally different (and rightfully ridiculous) thing. I am not suggesting bottomless clothing = any invite to anything, however I chose to dress tactically for the environment I plan to be in. From shirt to shoes to whatever covers my legs. I was in an environment where upkilting was likely, I would probably wear something else, same as if I was going to be in thick brush or spiny plants or walking on broken glass or hot furnace slag.
Yes I would go out into the world assuming there would be jerks with shoe cameras everywhere. And I would make it difficult to catch me and more difficult for them to remain walking and capable of reproduction afterward. I have a fondness for knees. And every jerk with a shoe camera usually has two of them.