There are places in the UK where you can catch a ferry round-trip to Europe for less than 100 quid. There are places in almost every European country where you

There are places in the UK where you can catch a ferry round-trip to Europe for less than 100 quid. There are places in almost every European country where you can catch a train to another country for less than 100 euro. Unless you're traveling to Mexico or Canada (which are just not that different from the US in terms of infrastructure), Americans face at least a $500 round-trip plane ticket and around 10 hours of travel each way. More realistically, ~$1000 for a ticket at a reasonable time between reasonable points. It's just a different order of magnitude of cost to visit places with different infra and culture.