Comment by Fervicus

Having a lot of experience with trains too, I can confirm this.

In Europe the major exceptions are Eurostar (Channel Tunnel) and the Spanish high-speed network, where the major stations are like airports, with airport-style security, airport-style departure lounges, and waiting. As I understand it, the extra security is at least partly an outcome of the Madrid terrorist bombings of 2004. Terribly self-defeating.

In France by contrast you can still arrive 2 minutes before the TGV departs.

Concerts and things like sporting events in the US typically require any bags to be clear and only be of a certain size. They may also be checked. No outside liquids are typically allowed (mainly to avoid alcohol). Usually people are at least wanded to prevent weapons, but sometimes metal detectors are setup.

You're very fortunate, you'll have to teach us your ways some day

There are even restaurants in London you can't get to without going through a scanner. E.g. half the restaurants at The Shard.

But to give an idea of how idiotic it is: Those are on the 32nd and 33rd floor. Next door is the Shangri La hotel of The Shard, where you can walk straight in and take the lift to the 31st (no scanners), and change to a lift for the 52nd floor (no scanners).