Hong Kong Protests Show Dangers of a Cashless Society

Physical cash is material technically government-controlled and -produced, but people can freely trade it with great independence.

I don't think we'll have a big problem here. People's drive to freely trade critical resources between each other is so strong that they'll create their own currencies if they need to - which is exactly what the burgeoning ecosystem of cryptocurrencies already is.

Taking public transport to get to the area of the protests might have not been the best choice anyway.

I mean, is it so far-fetched that the queues at vending machines are monitored and recorded by security cameras and facial recognition can be later used (syncronized with the actual ticket emission time) if the government wants to know who went where?

I see from the photo of the linked within article:

https://qz.com/1642441/extradition-law-why-hong-kong-protest...

that many people wear surgical masks, but I dont think that would be an issue if the governement wants to identify someone.

And there is no need of a pre-made database, it can be built later, assuming that the holder of an Octopus card re-uses public transport, you film him/her next time.

https://vimeo.com/27653912