Just for curiosity's sake, did any other EU countries have any recent terrorist attacks involving bombs on trains in the capital, or is Spain so far alone with this experience?
Edit: Also, after looking it up, it seems like London did add temporary security scanners at some locations in the wake of those bombings, although they weren't permanent.
Russia is the only other European country besides Spain that after train bombings added permanent security scanners. Belgium, France and a bunch of other countries have had train bombings, but none of them added permanent scanners like Spain or Russia did.
Notice how these inefficient processes create large, compact lines of passengers, which would made the casualties much worse in case of an actual bomb.
Let me go on a tangent about trains. In Spain before you board a high-speed train you need to go though full security check, like on an airport. In all other EU countries you just show up and board, but in Spain there's the security check. The problem is that even though the security check is an expensive, inefficient theatre, just in case something does blow up, nobody wants to be the politician that removed the security check. There will be no reward for a politician that makes life marginally easier for lots of people, but there will be severe punishment for a politician that is involved in a potential terrorist attack, even if the chance of that happening is ridiculously small.
This is exactly why so many companies love to be balls deep into AWS ecosystem, even if it's expensive.