To be honest, I'm surprised that crew rations (except for trips of over 5 hours) weren't binned years ago.
But a trip of, say, 4 hours, involves at least 1 1/2 hours before & at least 30 mins after (or possibly a great deal more if parked on the south side of EGVN & waiting to cross the runway) so that's at least 6 hours on duty & unable to go to the mess for a meal. The butty box makes an attempt at nutrition to tide you over that period & when measured against the operating cost of the ac it's hardly the biggest consumables cost.