Most decisions would be made via consensus discussion in individual mutual aid groups.
When groups needed to work together for a common purpose, only those people directly involved with the decision would form a temporary group and work by consensus.
If consensus cannot be reached in a reasonable time period, then the groups would need to be re-formed with new participants.
Every decision is made at the lowest possible reasonable level. If you think about it, it makes no sense that in our current system, I vote for someone who impacts the price of fuel in Cleveland (I'm not close to Ohio).
Any group of people today with a common purpose can make decisions via consensus. Why don't you bring up this possibility the next time you're in a meeting?