What if you get on the plane and realise that the seats are so close to each other that you no longer fit in the seat with the next seat reclined? Are you expected to research the pitch values for each aircraft used by each airliner before purchasing a ticket, lest your kneecaps get crushed?

I find it hilarious that you're downvoted for "tall people should pay for economy plus" while "fat people should pay for two seats" is near the top of this very discussion. As a tall and thin person, shame!

That's not always possible on every flight. Every airline has a different system and set of rules. Some airlines don't offer a system for paying for emergency exit seats. Other times the seats might already be booked. Sometimes the cost is prohibitively expensive.

When that happens you're stuck with the situation of having your knees caps smashed, just so someone can tilt their seat back a few degrees.

It's a very strange situation to agree that someone should have a small privilege to the discomfort or even pain of someone else.

That makes 0 sense, why should the longer person pay tax for their genetics? Also don't recline if it causes physical pain to someone else. Wtf is wrong with you