Comment by bzzzt

It would be more efficient for travelers, but not really from a systems point of view. The Netherlands is densely populated and its railways are amond the busiest in Europe. If twice as many people took the train it would be impossible to have enough trains running. Also, a money handling system functions as a gatekeeper. With some regularity there are stories in the media of people misbehaving on public transport. If everybody has the right to board it's more difficult to keep those people out.