The "What if everyone did that?" argument is currently a weak one as I suspect right now very few people want to use public transport for leisure purposes as nothing's open for them to visit. The only people you're likely to get on, say, a Hope Valley stopper will be individuals or small groups having a walk in the hills, where they'll come into far less contact with others than they would if they'd met up in their local park. The tourists will continue to stay away because the attractions, pubs, cafes and shops remain shut so there's nothing much for them to do.
You also have to bear in mind that repeated surveys show many people have been so scared by the more extreme proprietors of the lockdown message that they would not want to use public transport until they feel it's safe to do so.
Yes there will come a time when everything opens and there'll be a risk of public transport being overrun. But right now I see no good reason for denying the small number of leisure travellers from travelling by train so long as they avoid peak times.
I must admit to getting sick of hearing this constant moaning about public transport. None of us has a God-given right to it, and at the moment it’s - rightly in my view - being focussed on essential journeys, with the intention of supporting the economy back to work. With multiple billions in public funds being haemorrhaged every week on the economy this has to take priority over what is, by definition, non-essential leisure use, and with many things not open the leisure use likely at the moment isn’t the sort which is going to contribute much to the economy.
Once things settle down and we see what trends emerge around how people travel to and from work (as well as other essential engagements) then no doubt they will look at what can be done to accommodate others.
At the moment Boris’s £100bn six-month bank holiday needs to be wrapped up, and public transport needs to be fully focussed on supporting that. We simply cannot have a situation where capacity isn’t there for work journeys, and nor can we have a situation where staff safety is compromised unnecessarily.
We also need to move away from this notion that “the trains are empty so there’s room for leisure use”. Not every train is empty for a start, and it won’t take many leisure journeys before they’re not empty again. Any empty space needs to be utilised for work-related journeys first.