Aircraft operate in three dimensions and must take into account various weather conditions, other air traffic, etc. Aircraft have autopilot.
Trains operate for the most part in one dimension are less affected by weather conditions. Aside from maintenance, keeping them operating safely essentially involves controlling one variable: speed. Trains don't have autopilot?
I must be being greatly naive. I must be missing something. Certainly, when an aircraft crashes, it's big news and often fatal for everyone on board. Perhaps this tends to drive research into making planes safer more so than with trains. I mean, how hard could it be to have someone at the controls of a train who is paying attention and isn't at risk of falling asleep at the wheel?