I know it's "technically" not fare evasion. But to any ordinary member of the public who pays the correct fare for their journey, the following situation...
- Customer: "Hi. My meeting's finished three hours early. I have a ticket for the 21:10. Would I be able to hop on this train (19:40)?"
- Train Manager: "Yeah, sure. It's very quiet anyway."
I'm going to disagree with you there, I don't see the harm in asking at all! I would have thought yield management practices would mean that the company is very happy to use an otherwise empty seat on an immediate departure they have no chance of selling in the hope that they can sell the seat you vacated to someone else paying the last minute walk up fare later.
The last time I held an airline ticket in similar circumstances they couldn't wait to grab the peak evening ticket out of my hands and give me an off-peak afternoon ticket and get me on my way two hours early, though I suspect they had already oversold the peak flight.
Its an "everyone wins" situation in my book (well other than the airport that lost out on selling a few beers to me!)