I am not aware that European carriers would put passengers luggage on an earlier flight - it never happened to me and our luggage (but, until I did read this post, I wasn't aware that US carriers do either ...).

But I am aware that there is always luggage on board on any of my flights that originally should have been travelling earlier (and missed the connection, got lost, etc.). And there is unaccompanied freight on board too.

It is not difficult to make my luggage to miss my connecting flight(s) by purpose if I (or a terrorist) would want to do so - I once forgot, after a transatlantic flight on UA (FRA-ORD) to pick up my luggage in ORD (before costums) and recheck it for the continuation ORD-DEN-ASE. UA did bring it through ORD-costums and sent it the next day (I reported the luggage truthfully in ASE as forgotten in ORD and UA helped me out free of charge). Thank you UA (and I hope costums and security check carefully such luggage).