Perhaps what you say concerns UK but is not quite accurate in EU countries.
Young people throughout Europe learn early about the neighbouring countries and cultures. They learn more than one language. Shared foods, customs and ease of travel bind European youth cultures together. When they are old enough, the freedom of movement enables them to cross borders for work and further education. All this is not only restricted to the wealthy, nor do they regard that as a reason not to explore.
The ‘island mentality’ within UK begins with inadequate state teaching about other countries and cultures. This, over generations leading to xenophobia at its most extreme.
Brexit has done a huge disservice in preventing young British residents from freedom to discover Europe. Perhaps some are not the least curious to leave ‘their parent’s box room’ but whose fault is this? And that is by no means the majority of young people, whose curiosity and wanderlust should be lauded. They are citizens of the world.
This old SF thread is interesting and reflects the reality of many parents today