I’m not in denial that someone somewhere at some time has taught Lolita at the HS level, but the suggestion that it’s common and “taught in a lot of high school classrooms” requires evidence. The same reason you find that idea infuriating is the same reason I don’t believe the assertion is true.
As for your evidence, only the first link has anything to do with HS classroom, and it’s a single teacher teaching it in some capacity - not a discussion of school/district/state curriculum or an indication that the text was required reading. None of your other references have anything to do with HS curriculum or indicate in any way that Lolita is being commonly taught at the HS level.
There's a lot of denial about the state of schooling. Most adults assume the school they attended in their youth is basically the same today, or maybe a bit worse, but it couldn't possibly be exponentially worse.
I was specifically speaking from my direct professional experience as a HS English teacher (in more than one state, including time doing curriculum review committee work across statewide districts).
Yes it is taught in a lot of high school classrooms in America and folks love to pontificate with their weird justifications for it!
1. https://www.journals.uchicago.edu/doi/abs/10.1086/691255?af=...
2. https://www.insidehighered.com/views/2018/05/14/teaching-lol...
3. https://highschoolbooks.home.blog/2019/02/08/you-probably-sh...
4. https://www.thenabokovian.org/comment/71
5. https://www.aclu-or.org/en/news/lolita-and-freedom-read