regarding lice: honestly, when I was growing up in the Houston suburbs (in the early-mid 90's) I never heard of anyone in school having lice and we certainly never got checked for it. It just wasn't on the radar screen. So I have to admit, seeing cases of head lice treated as just part of growing up here was really weird for me. But obviously, my experience was just in one little corner of the US and after educating myself I see that it's common in both countries- but if you haven't been exposed to that before I can totally see why the lice thing would give someone pause.
Just along the highway from Houston, in Austin, lice was "part of growing" for more than one family I knew there, not just in the UK.
I too never had lice and never knew of a case of lice; I grew up in London. We did have a nurse come to the school and do regular lice checks. But I never heard of an outbreak However, that didn't mean that they were not a "normal" feature of childhood; everything else I've gathered from others I've encountered in both the US and the UK tells me that they are, even though I myself, like you, never had an experience of it.
Edit:
Having said this, I think it's important to point out that even people who understand that it's very common in school-age children of all classes and in both countries, still don't feel fine and dandy about having a case of them. In both the UK and the US, a case of lice is still something that draws a reaction of horror in the family involved -- I say this lest anyone think that just because it's accepted as relatively "normal" doesn't mean its accepted as okay. People still don't want or feel good about finding their kid has lice!