Every family does ‘big’ celebrations differently - I don’t think that’s an issue. I was one if the ‘wouldn’t dream of charging’ folk - but I am also hosted elsewhere over the festive period so I see the meals I host as my contribution. When I stayed as a guest - even as an early 20-something graduate on a very crap wage - I took a contribution of food or other sundries, whatever my parents requested. It might have been crackers, or napkins, or cheese, or fancy biscuits. Whatever - we contributed according to our means. As I got better off, it was a case of wine delivered etc.
I grew up with my grandparents and then my parents hosting the whole extended family for days. For us as kids, it was amazing! It’s only as an adult I appreciate the various issues on all sides that everyone sucked up (mostly) happily. The travelling side of the family contributed cash towards the butcher’s bill, plus a pub meal out at some point for the chef’s family, plus liqueurs/chocolates/extras.
It is perfectly reasonable and normal to divvy up the cost whatever way makes sense, given that nearly everyone will be expecting to spend a bit extra on a celebration at Christmas, whichever house they’re at, so it’s hardly terrible hosting etiquette.
I also strongly agree that unless you’ve hosted you don’t realise the whole expense, so perhaps OP is being a touch light in the estimates of the price per head...
But the OP says they’re being charged twice what they’d budgeted, AND someone else drank the booze! That’s awful. It really can’t possibly be justified!