Originally Posted by dls25

JAL international crews only do out and back international trips.

US carrier crew scheduling is much more complex. The FA might be on reserve or scheduled to go to Wichita and they get reassigned to a London flight at the last minute after a sick call. If they check bags, they might not be able to take the reassignment because there is not enough time to check the bag or they have to delay the new flight because the FA has to get their bags out of the hold of the flight they were previously assigned to.

That is why US carrier FA's do not check their bags.