The fear is the use of an airplane to crash against a building with people inside--i.e. to use the airplane as a weapon. The train can "only" be used for terror

The fear is the use of an airplane to crash against a building with people inside--i.e. to use the airplane as a weapon. The train can "only" be used for terror: to threaten to blow up some people. If you cynically add that government high officials are unlikely to use a train and very likely to be targets of an airplane used as a weapon, you get why traveling by train is still a pleasure.