The whole process of booking seats on public transport is a potential nightmare. People sit on your seat and then you have to fight with them so you can sit down, or you may find that you have accidentally parked in a location reserved for someone’s aged relative. In either case, embarrassment ensues.
Today’s invention makes booking a seat a well-defined event. Instead of attaching an inconspicuous piece of paper to the back, train staff flip the base around a fore-aft axis marked X. This locks the seat with a number of random-height hoops sticking up. Impossible to sit on or even put a case on. No danger though of causing anyone injury.
When the seat owner appears, they unlock it using their credit card (or via a keypad), flip the base and sit in upholstered luxury.
A smarter system might have remotely powered seat rotation setup in direct response to the booking computer’s signals.