What is the biggest culture shock you have ever faced?

When I visited the United State as an exchange student, I was shocked by the way they threw away garbage. They didn’t separate trash, but we do that relatively well. They even threw away paper, food, plastic, rubber, and everything else in one place. I didn’t understand what they were doing ‘cause it could cause environmental pollution. I think the global environment depends on how they throw away their trash and deal with issues of pollution. It’s because the United State occupies a big part of all kind of industries.