I do think that people are generally good and they generally mean well and given the chance, most people will do the right thing. Unfortunately, that's not always the case.
At Six Flags Fiesta Texas we had time for maybe two more rides before the park closed. So Oceanus and I got in line for a roller coaster (Poltergeist). The line should have been about 10-15 minutes long. However, there were a group of young twenties ahead of us. They yelled at a friend and 4 people joined them (cutting line). Okay, that sucks and it's wrong, but whatever. Then it happens again. And again. And 3 more times. All in all about 24 people ended up jumping the line in front of a lot of people. This added about 5-10 minutes to our wait. Goodbye to the chance to ride another ride. Surprisingly enough, no one confronted them about it. Some people grumbled about it, but no one lit into them.
At SeaWorld there was a woman saving a whole row of seats in the 4th row (really the best row in terms of being able to see well) for the last showing of Shamu. We got there about 30 minutes early and ended up in the 2nd row - not bad seats at all, we couldn't see as much on the surface of the water as we'd have liked, but still not bad. We never saw the rest of her party. Not when we got there, not later. Finally, they've chained off the openings and aren't letting anyone else in - but still she's saving these seats for people who have "gone to the bathroom". Clearly she was sent in to save seats while the rest of her party enjoyed rides, etc. Finally people started sitting in her saved seats. They had no where else to sit and no one else was being let in. She got very irate and apparently ended up cussing out a 14 year old girl (who to her credit immediately stood up for herself and said "Don't talk to me like that! You don't even know me!"). Last I heard, the woman was escorted out of the park.
I understand her frustration. She was put in a bad situation. Her party sent her in to save them seats and then selfishly didn't come to the show in a timely manner. She's stuck trying to save seats while people are sitting 4 in a spot that would normally fit 2 people (Hyperion ended up sitting on Mr. Gaia's lap) and I became more intimately acquainted with the strangers next to me than I really like - I was sitting closer to them than I do to my own family.
I think the SeaWorld folks really should have gotten involved much sooner. There was a guy walking in front of our area of seats and there's no reason why he didn't notice the escalating situation.
I do think that we were very lucky to only see these two situations. For the most part people were extremely friendly. I'm that weird person who starts up conversations with perfect strangers while waiting in line. No one gave me the hairy eyeball and shunned me. They all talked with me and told jokes and helped the time pass much more quickly.