You could still take their details and record the occurrence, but then you'd give them "points" on their "license", fewer points for having a ticket but been on the wrong train (advanced tickets etc) or forgetting to tap out, more for shadier things, and the more the potential financial gain, the more points (like getting more points for doing 90 on the motorway than 80)
So we would need a "licence" to travel by rail?
If I left my "licence" at home would I get points on my "licence"?