I've always been confused why if you buy a ticket, you can't get the miles if you don't fly. And if you want some extra room on a flight, why can't you buy 2 or 3 seats and stretch out.

If you don't fly, they give your seat away. And you can't get any mileage credit unless you are actually in the air, even though the airlines have your $. Why do they care?

Air travel seems like the only product you can buy, and get charged a fee if you change your mind even 9 months before your flight yet the airlines can change the flight 10 times and you get nothing....

Can anyone offer any logic to this air travel weirdness?