You can expand that to other systems. For example you can walk onto a city bus in many cities without proof of payment. It is assumed the vast majority of peo

You can expand that to other systems. For example you can walk onto a city bus in many cities without proof of payment. It is assumed the vast majority of people will have paid by tapping their transit card somewhere, or purchasing and activating some mobile-based e-ticket. Same with many commuter trains. The result is faster more streamlined service for everybody. I find the cryptocurrency "space" fascinating for reasons like this. Because cryptocurrency gets rid of so many of societies long-evolved backstops, it is a perfect demonstration of why our society is structured the way it is and shows exactly what happens when we remove many of its features (eg: removing "trust" is very expensive).