I should have been more clear in my comment, I was referring to international high speed trains. Including mandatory registration of passengers and keeping the data for X years. Presumably these passenger manifests are also exchanged with other countries.

But even regional services include oodles of cameras, including on the trains. There's tracking of passengers and their destination. There are heavily armed guards/police/soldiers in many European train stations.

Hmmm...those trains I step onto are (a) typically high speed and (b) quite often "international", though the concept really doesn't make much sense in the Schengen Area.

Are you talking about the Eurostar service from London (I remember the Waterloo station, though I hear it has moved to St. Pancras). That's the only one I can think of that fits your description.

The Thalys from Cologne to Paris via Belgium is/was also simple walk on walk off with normal train stations.

The Thalys has security theatre with luggage x-ray in several locations, including Paris and Antwerp. It's currently not active 24/7, but it will be soon.

On the TGV from Luxembourg to France, there were no barriers. And nobody ever asked me for my ID; in one of the legs, they didn't even check our tickets.

I don't doubt they keep those manifests, but I've found very little actual control.

Brussels does have troops going around, which is unsettling, but I never saw them inside the actual station, nor stopping people entering it, even after that poor devil immolated himself last year.

Not true anymore in every NL station : we have entrance gates, no ticket, no entry to the boarding area.

Curious. Is that very recent? I was in Amsterdam last year and while I remember the ticket validators, I don't remember them being mandatory; I think we've even passed them to cross the station to the other side, to catch the ferry.

It is recent, not everywhere and loosely enforced. But the intent is there.

The situation in A'dam : I guess it is impractical and unwanted to close the corridor from the one end to the other.

In Utrecht they recently closed the main corridor from one end of the station to the other (which, unlike the Amsterdam station, also splits the city in half).

Fortunately, they left a relatively narrow outside corridor open. Still feels odd to have to check in and out again when you're coming from or to some of the main busses, or take a detour.