That's a skewed conclusion you're drawing. Are you really surprised that people aren't willing to risk escalating the situation on a plane, arguing with what's likely the very inconsiderate person in front of them? Most people have an aversion to conflict. It doesn't mean "they're fine with it". You probably don’t advertise in real life how much you lean back and not care who’s behind you out of fear that people will change your opinion of you. Real life is a harsh mistress.
I've bumped into people and they said "sorry", do you think they wanted me to bump into them, liked it, and actually believed it was their mistake? No, I just tower at close to 2m so they didn't want to escalate the situation.
P.S. I always look at who sits behind me, if they're "space constrained" or not, and almost always ask if I can recline. Sometimes I don't bother, clearly the person will suffer. Sometimes they said "I'd rather not, thank you". Many times they said "fine". I used to fly a lot and my experience was very clearly not that "everyone is fine". I was never fine even if I didn't start arguing. So how would you have known?