It should be a free service anyway. Without free public transport, democracy does not exists. Same reason healthcare and education should be. So sure, you are “stealing” a ride - something that should be yours anyway because people are not born with the ability to travel kilometers of cityscapes, something that is now mandatory to survive and thrive.
And by the same principle, you could shine a powerful laser towards a very reflective sail and actually move, with the laser as a part of the boat.
I too always found this very funny. Confuses the hell out of people who just understood why the OP would not work.