A couple of points:
1) Re the OP
apparently its discriminating against those with children
is clearly nonsense and in fact the opposite is the case – the assertion is that the childless have less “dibs” on those dates so if there’s any discrimination going on, its against the childless.
2) There seems to be a lot of confusion in this thread conflating the need for parents to book leave during school holidays and “going on holiday” with comments about how much that costs. Do those making those comments not understand that, for younger kids, the need to be on leave may well have nothing to do with “going on holiday” and everything to do with the fact that the kids can’t just be left at home alone to fend for themselves and so, in households were all the adults are in work, someone’s going to have to take leave to look after them?
Same with the comment a page or two back moaning about parents needing time off at short notice if their kids have “a sniffle” or something – what are they supposed to do? If the school sends a seven year old home poorly, they need an adult there, don’t they? You can’t just tell the school no one’s coming to pick them up until normal time because work are being a bit sniffy about it. And lots of schools have policies about not allowing kids back for a certain period. If my youngest pukes in the dinner hall today, they won’t let her back in school tomorrow. Either me or the wife is going to be at home tomorrow then. Employers have to be reasonable about this (legal requirement).
None of which goes anywhere near justifying banning of leave for the childless during school holidays, as appears to be the OP’s situation btw.