Obviously you have not met my BIL. I've know him for 18 years, and he's terrible at communicating and staying on schedule.
I prefer talking to his wife, who gets to the point, and gets it done right.
The poor communication comes from my wife's side of the family. Everything is left uncertain because someone doesn't check their text; or things or intentionally left vague so noone's fee fee gets hurt.
Anyway... after they came over, and I got his side of the story, I'm filling in the blanks in the timeline.
(3:55PM) Wife orders food independently from her brother since she didn't hear back from her brother. He had guest at his house and didn't check his phone.
(4:20PM - 5:50PM) We yada yada'ed at home.
Some time between 4:30 and 5:50, my BIL finally steps away to make his order. I'm guessing it was closer to 5:50.
(5:50PM) Wife leaves to get ours AND their burgers.
(6:20PM) Our immediate family eats OUR cold burgers that were ordered at 3:55PM
(7:00PM) BIL's family FINALLY comes after their guest leave to eat their burgers that were probably ordered at 5:50.
TLDR:
The original plan: BIL orders, pays, picks up the food; everyone eats together, early, at their house.
What actually happened: We order and pay for our own food; he orders and pays for their own food; my wife picks up both orders; we eat separately, late, at our house.
I was so flabbergasted that I didn't want to talk to my wife or BIL afterwards.