Airlines make the seats smaller (17" to 18" wide) and closer together so they can cram more of them into the aircraft and thus have more paying customers on any given flight, THEN say if you can't fit into one of our ridiculously small seats, we'll charge you for two. Oh, and we're only doing this because of the high number (almost 800) of complaints we've received from other passengers.
Hmmmmm, strangely enough they haven't bothered to respond to the THOUSANDS of complaints they have received about extra baggage charges, snack charges, scheduling changes, flight cancellations and generally poor service across the board. They've only responded to the complaints that they can turn into a revenue stream for the airline. Hmmmmm.
Now, I fly quite a bit. I myself am a large person (6'4" and 260 pounds), but I'm always careful to not intrude on a seat mate's space because I know I don't like my space being intruded into. My travel agent knows that my preference is to sit in an exit row window seat, if for no other reason than it gives me a bit more leg room, and they always try to book such a seat for me when possible. On any given flight I'd rather be mashed up against the window than hanging out into the aisle to be pummeled by flight attendants, people walking the aisles and drink carts
I HAVE sat next to people, both large and not, who "flow" into my seat space. Yes, it's aggravating. But even more aggravating are the loud talkers, the screaming kids, the people who don't control their kids, the people who kick the back of my seat, the people who recline their seat back into my space, the people who bring their surfboards, skis and golf clubs on board as carry-on luggage and the flight attendants who will do nothing about any of the above. Can we charge all of them extra as well?
I thought not.