Do not get into that debate with an economist
Suffice to say almost all travel on the railways is want and not need.
I do not need to work in a different place to where I live, but I do and that generates revenue for the railway. Aside from some cases of low paid workers needing to be further from their places of work due to property prices being inflated near those work places rail travel need is very low. I have to single our groups who could not afford an alternative private means of transport, and for whom bicycles would not be a workable option. Even then there are ways to provide alternatives to rail travel such that rail travel is not needed.
Thankfully, we have not gone down the need route and so we have services that provide for wants. People want to travel on Boxing Day for many reasons (which then answers the demand for Boxing Day travel question).