[kwhitefoot]

For all those saying that there are no security checks on trains: perhaps you have never been on the Spanish Alta Velocidad from Zaragossa to Barcelona. When I took that some years ago my luggage had to go through an X-ray machine and I had to go through a metal detector.

I don't know if they still do that but it is certainly something that could be instituted if governments wanted it.

[dredmorbius]

There is of course some history and justification for that.

2004 Madrid Train Bombings:

https://en.wikipedia.org/wiki/2004_Madrid_train_bombings

[EdwardDiego]

I had to go through security and customs getting onto the Eurostar in London, but that makes sense considering they weren't part of Schengen.