But... train driver roles in this country do not exist in a functioning market. On one side it has very strict restrictions on line and traction knowledge, with relatively limited transferable skills and a with a high training cost, and on the other collective bargaining where the union hold most of the good cards, and know it.
I would argue that driving a train is a harder job, because of the knowledge you need to learn and retain, and the implications of making a mistake. Drivers I know will freely admit that for 90% of the time driving is easy, but the other 10% it is rather hard. Eg driving in fog or driving rain, at night, at 125mph, unable to see anything other than the lamps of the signals, no idea if there’s something on the line, etc. Needing to know exactly where and what the speed restrictions (permanent and temporary) are. Knowing your braking points so you can stop exactly in the right place. With several hundred people relying on you to get to destination safely and on time.
However I would argue that an airline pilot is a much more demanding role. Firstly you need a higher level of education. Then the training - more of which later. And when you qualify, you then have to do several thousand hours of flying at second officer / first officer / co pilot before you might eventually become a captain - perhaps 7-8 years later. During that time you will be flying an aircraft where you are responsible for much, much more in terms of the action of flying than driving a train. Prepping flight plans. Calculating various critical metrics pre flight. Supervising fuelling and pre flight checks. Flying the plane, and being expected to take the correct immediate intervention action if any one of hundreds of potential failure scenarios occurs. Landing in crosswinds in a storm (I’ve done this on a simulator, and it was the most challenging ‘driving’ I’ve ever done, far more so than any train driving). Post flight reports. Keeping your own training and competence logs. For most of the time before you make captain grade, you will be taking home less than a typical train driver in this country (certainly less than what the drivers I know take home).
And the training. For most airlines, you pay for it yourself. Make sure you have £120k spare,which you don’t get back if you don’t make the grade.