I'm not talking about a small community, we are looking at up to 100 people per location.

It gets difficult to keep a tally of who owns what and when. The kumbaya lifestyle where everyone has good sense doesn't scale.

If you work for a week planting the field of someone, you need payment for that. Attention that time can be traded for other goods when both parties agree. Also, time from diferent people has different values. You might work the fields for a week and just get 60 minutes as payment reward from someone important.