Read what I said - I said most people can but they don't have to. Can the store manager in a supermarket justify why they are paid more than the cleaner in the same store? Of course they can. Arguing they can't would be ridiculous. What about the store manager of the supermarket earning more than a train cleaner? Of course they can. What about the store manager earning more than a station ticket office clerk? Again they can. What about the train driver earning more than the store manager? Harder to justify and it seems train drivers don't even want to bother trying. Then what about jobs which pay more than the store manager but less than a train driver?
You really don't have a clue.
As someone who has done both jobs mentioned here. I was a Retail Store Manager and I'm currently a Train Diver. I can assure you that driving a train certainly commands more remuneration on so many levels.
There is also a vast difference in skills. Comparing the two is pointless. You are also forgetting that there are many levels of 'Store Manager' The Manager of my local Tesco Metro store gets a good £10k more than me but other Store Managers get paid a pittance.
Basic retail managers vary quite considerably. I worked in 2 different sectors and saw a wide variety of salaries. Supermarket are very management heavy with extensive tiered systems with General Store Managers topping the scale and pushing north of £100k. There are various routes into retail management and many of the higher end stores offer various graduate programs; especially as their Managers tend to be a bit more qualified and have a fair bit of oversight and considerably more responsibility. The lower end and mainstream retail stores pay a pittance and the route up the ladder considerably easier. I started as a Stockroom boy and ended up in charge of a team of 60 and a two floor, champion store. I've seen salaries as little as £13k to £200k. I was working 70hr weeks as a Manager with little recognition and very little pay. I could have gone higher up the ladder but choose to leave the sector.
As a Train Driver my skills are more physical and mental. I do less hours but there are obscenely unsociable (note the time posted) I am responsible for the safety of 4/500+ people on a trip and a single mistake can cost lives. It weighs heavily. I am also in a job where I can potentially kill someone and my first week on the job a colleague killed a teenager who decided to sit on a foot crossing in the middle of the night. I also went through extensive training and assessments. Whilst that could be compared to a Graduate program neither job needs any previous qualification and can be wholly vocational. As a Train Driver I am also 100% pretty much all the time. I have very little downtime. I eat and pee when I am scheduled to do so. As a Manager I sat about in an office, downing tea like it was going out of business. Train driving is very constrained in what you are allowed to do.
The jobs are very different. I feel that I have much more responsibility as a Train Driver. I work a lot less hours than I ever did in retail but I have a lot less flexibility. Retail didn't pay and it would have taken a bit more dedication to push up to higher management and the beauty of being a Driver is that I get paid for what I do and that the way in which we are so constrained by the DRI and T&Cs etc means that I cannot be taken for a ride. It's been said before on this forum that Managers are expected to put in the hours for no reward and no overtime. Retail has some serious sharp practice. Train driving has less opportunity that retail and a decent Retail Manager can turn their hand to pretty much anything in their store which allows lateral movement within the sector. As a Driver I am almost limited to just being a Driver for the rest of my career; which in all honesty is something that many of us crave.
As to a job that paid more than a Store Manager but less than a Train Driver. I went from Manager to Multi-drop Driver. Multi-drop paid more