It’s a crass example, but when you ship freight, you pay by the or bulk of the package; the heavier/bigger, the more you pay – because it takes up more room Animal liberation for all vintage shirt . And space/weight you pay for is reserved for you and cannot be occupied by anyone else’s freight. You paid for it, you own it. So, when I pay for my one seat (as much smaller as they are getting nowadays, it’s not a better bargain), I have a contract for that much space; and my armrest is NOT coming up to make room for their excess bulk. Or, to put it in another way, it’s not much different than the person who takes up two spaces in the parking lot or garage; or the neighbor who ‘parks over the line’ and intrudes on your space; or parks their vehicles in front of your house instead of theirs.