Fire hazard maybe? Trash cans were removed from commuter trains in Stockholm since they were constantly being set on fire. They're on our buses though.
Go to England and you won't see trash cans in train stations at all.
In England we do have bins in stations, but now days they generally consist of a transparent bin bag with no surrounding material (e.g. held open by a loop at the top that's attached to a wall). I believe the logic is that it makes it harder to hide a bomb in them, though whether this is fact or just commonly quoted myth I have no idea.
Partly correct. Trash cans were removed to prevent people hiding bombs in them. They are now coming back, both as transparent plastic bags, and also as bomb-proof cans (which are designed to direct the explosion upwards, and resist sideways rupture).
Go to England and you won't see trash cans in train stations at all.