I am accountable for MANY train drivers in my role, plus have done a fair bit of flying and worked in ground ops for a UK airline.
Let me assure you there IS a big difference between train drivers and pilots, I wouldn't put half of the individuals I know in the seat of a tug let alone a seat on the flight deck. Please don't use the salary as a comparison in technical ability, and professional attitude. They are not in the same league!
There are some very good people out there wasted driving trains, but there are many more.....as above!