Just like Disney World - they scan your finger print upon entry to the park. When you ask to opt out, they're like "Well you're going to need to step out of line over here and give my manager some information.."

Not to mention that you usually don't know about it until you get there, so you don't have time to look up anything about it to see whether you can avoid it. I read about it after buying my last ticket and learned about the passport thing, but that was because I'm interested in what the TSA does and follow security and privacy blogs.