Is there such a large, morally important difference?
I am going to simplify a lot here, but let's say that the train operator has a fixed operating cost and has a profit target, from which they know the gross revenue that they want over the next quarter. They know how many rides they expect people to pay for, so they divide the target gross revenue by the number of trips to get the ticket price. Assuming that the train timetable is fixed, more paying passengers means they can charge less per ticket and still hit their targets.
So in the case of stealing from someone's wallet, the victim takes a $50 hit. In the case on not paying for a train ticket, the operator will have to charge a slightly higher rate to paying passengers, so between them, the paying passengers take a $50 hit. If there's only one person not paying then that doesn't make much difference. But if 1% of passengers aren't paying, or 10%, or 50%... then that can start to affect the paying passengers quite significantly.
Or if the train operator is a bit less charitable and doesn't raise/lower the price in response to number of passengers, then the train operator's profit takes a $50 hit, which is passed on to the share holders, who may well be (in part) yours and my pension fund.
I would say that just because the $50 loss is divided by a large number of people, it doesn't make it any more morally defensible.
This would be a good (though not airtight) argument if the person would pay the $50 if he could not sneak on. But in fact, most people who torrent gigabytes of music would not pay for it if they couldn't get it for free.
In fact, piracy in this case seems to partially solve the fundamental economics problem. The marginal cost of music is zero, so if people who wouldn't pay full price aren't getting the music, then there is lost utility for society. By giving those people music for free (and, unrealistically, holding everything else constant) it's a Pareto improvement.
(And I'm not trying to avoid the argument that stealing $50 from society is morally he same as stealing $50 from a single person; it pretty much is. I'm just saying that the reason that we correctly intuit that sneaking on to a train is less worse than stealing from a wallet is because of considerations like those I've described.)
I am going to simplify a lot here, but let's say that the train operator has a fixed operating cost and has a profit target, from which they know the gross revenue that they want over the next quarter. They know how many rides they expect people to pay for, so they divide the target gross revenue by the number of trips to get the ticket price. Assuming that the train timetable is fixed, more paying passengers means they can charge less per ticket and still hit their targets.
So in the case of stealing from someone's wallet, the victim takes a $50 hit. In the case on not paying for a train ticket, the operator will have to charge a slightly higher rate to paying passengers, so between them, the paying passengers take a $50 hit. If there's only one person not paying then that doesn't make much difference. But if 1% of passengers aren't paying, or 10%, or 50%... then that can start to affect the paying passengers quite significantly.
Or if the train operator is a bit less charitable and doesn't raise/lower the price in response to number of passengers, then the train operator's profit takes a $50 hit, which is passed on to the share holders, who may well be (in part) yours and my pension fund.
I would say that just because the $50 loss is divided by a large number of people, it doesn't make it any more morally defensible.