Why are Germans so cheap?

I was on a Ryanair flight from Frankfurt to Dublin and most of the passengers were German. None of them ordered any sandwiches, coffee, or drinks while on other flights (Italians, Irish, English, etc) people usually order something.

Why are the german so cheap?

Do American airports treat overseas visitors badly on their first visits?

I hope I don't sound like I'm complaining or upset. I'm actually curious about the American view on overseas visitors.

On my first visit to America from Australia, when we arrived in LAX Airport, we were treated a bit badly - we had to stand waiting in an empty waiting room with others for 30 minutes, and even when they inspected our passports and before stamping them, they asked about how much money we had. When we replied that we had about $2000 in total, they almost didn't let us through anyway. It almost became an argument. Even when we were leaving USA, they inspected us as suspicious and looked through all our suitcases - which we didn't find out until after we arrived home.

But on the second visit to USA, we weren't treated like that. While the first time took an hour just to check out of the airport, the second time took about half an hour, and we were treated better - no asking about money or we were treated with suspicion.

Mum guesses because we're now frequent flyers to USA, we have a good record with them and the American airports now trust us.