Having being brought up with picnics and packed lunches being the norm for days out, swimming, etc etc (we'd sometimes get an ice cream or chips, but mostly it was food from home/supermarket) I find the people who always buy the food at attractions fascinating, especially those who complain about the cost, but it doesn't seem to occur to them that they could take food with them for much less.
Do they like spending a lot of money for what is usually rubbish food that they have to queue for ages to get? What goes through their minds?
I've just posted on another thread:
Typical cost of a sandwich, crisps/cake and drink at an attraction for a family of 4 around £30, possibly more, it could easily be a fiver for a sandwich, £2 for a drink and £1.50 for a bag of crisps.
Same food but bought as supermarket meal deals on the way there £12-15
Make sandwiches at home and drinks and snacks from multipacks, £5 or so in total.
Obviously some people can afford the higher prices, or there could be circumstances that make taking your own food impractical, but for most, surely you'd know that it's likely to be poor value for money to buy food while there and take it with you where possible?