Below 90% is about 18 missed days of school. If a parent takes them away once for 2 weeks and another time for 1 week during termtime, plus a few sick days, then it easily drops below 90%. Some parents tell the school, some don't, but it's blindingly obvious when a child comes back with an amazing tan in the middle of a rainy March, that they were not laying in bed with a tummy bug from Monday to Friday.
Heads in England where we are are only allowed to authorise in exceptional circumstances, there is a form we can submit to my daughters school if we think our request meets these, we have requested it twice, both a couple days for family weddings abroad, and both times it has been agreed. Our school is more flexible than most, it will agree time off for most family events etc as long as childs attendance is over 95%. I'm guessing your school is not in England?
Our school would also call a parent for a brief chat about their childs progress if requested, but this post was whether parents should be entitled to a parents evening appointment on a different date if they miss the planned one. Of course it's helpful if a school will do this, but I don't think a parent can complain if they don't.
Tbh the pre planned parents meeting should be nothing more than a brief update for a child who is doing well. If there are any specific learning or behaviour concerns then a good school wouldn't wait until parents evening to talk about this, they would be asking the parents to come in for a meeting.
We know that lower attendance correlates to poorer outcomes. Whether that is as a direct result of the missed days, or that those who are missing days also place less importance on their child's education and that impacts on their outcomes can be debated.
My daughter has 5 close friends from a wide variety of backgrounds. Talking with her friends about 'what do you want to be when you grow up'. Those with parents in professional roles came out with 'Children's nurse, teacher, archaeologist, photographer/explorer', other 2 said 'hairdresser and 'nail person', these 2 have several termtime holidays. Talking about university, these 2 were adamant they wouldn't attend, despite both being naturally very bright, brighter than my daughter and her other 3 friends. But the level of aspiration was very different, and the attitude towards school and learning was very different, it just wasn't seen as a priority. So that's what I meant earlier about getting stuck in a poverty trap, these children have a completly different mindset, which I found really interesting, and the challenge for schools in changing the attainment gap is as much psychology as income related.