If they do this knowing they are causing you discomfort is a case of I am all right jack!
I once had a stoppy bloke in front of me who recined his seat on my knees as soon as the seatbelt sign went off.
At this time I was in agony and could hardly walk.I stood up and told the stewardess I couldnt travel for nearly 5 hours with this bloke infront lying on my knees so the moved me to another seat.
Since then I have a home made knee defender which I use if the seat pitch is tight.
I will warn people who dont agree with this of my seat and flight number when I next go away so they can avoid being the unfortuate person infront of me.

