Cells in Europe have learned that every attempt brings intense scrutiny on every known associate, with an increased tempo of police raids and interrogations - they often lose more than they gain (even if no one gets caught, their ability to operate is severely hampered.) The old school terrorists, like the IRA, had a far superior support network to disappear in so they did indeed do dry-runs and diversions. The IS-inspired clowns aren't at that level and have to make each attempt count.
From what I can tell based on social media, they messed up a real strike; the power source and initiator worked but the explosive fell short of effect. Also, the placement in the middle of the train is a poor choice so the delivery person either wasn't trained or panicked.