last 2 times I flew I didn’t check in online and when they printed my boarding pass at the airport they put me on the seats next to the wing exits. Does every airline do this?
Unless the emergency exit is manned by the crew, they need a passenger there who can open the hatch if needed.
Normally this isn’t a problem, as someone usually prefers that seat due to the extra legroom. If there aren’t many passengers on the flight, and nobody has booked that seat in advance they might assign that seat early in the process so that someone who isn’t fit to sit there can have someone else take their place.
A few times, on smaller flights with free seating, I’ve been asked if I can man the emergency exit. I normally sit far forward on these flights, but I don’t care hard enough, so I’m happy to oblige.
As for who can sit there, it’s not a particularly high bar: any adult who is reasonably fit who is comfortable with being responsible for the emergency exit.
Source: Partially through observation, plus I had a chat with a stewardess on the topic not that long ago.