Introducing a new local currency after an event

[grumpy old man]

hi this is what i think would happen?
after an event people would have to help each other for free. i am not saying give you food away but help each other social commie's but i can't see a way to turn this into a business mode.
what would we use cash, water, food, gold, bullits, etc, etc.
and who would set the exchange rate?
would we have little barter towns with a tax to be paid to the town king
and what if you really needed a doctors service or something to save your family and you could not afford it, what would you do to get it.
and how could you trade with the level of security you would need to stop being robbed.
this is why i think for long term survival a social commie is the only way with no king's and everyone playing a role. no one living of other people just like how a home works jobs to be done and keep the clock working and no one person having complete control.
again i don't know how this would work either so i try and not think about the future to much.
headaches or bad for you. lol.