Tap and Go works the same way Myki does
Card tells reader “I’m card 6742069”
Reader tells server “card 6742069 just touched on at South Kensington at 4:20PM”
Inspector wants to check ticket, ticket tells handheld scanner “I’m card 6742069”
Handheld scanner asks server “when did card 6742069 touch on?”
Server responds
Ticket inspector arrests you for feet on seats
Your family leave you
You die in prison