I think we’re confusing pragmatarian and non pragmatarian situations.
AIUI in a pragmatarian situation all goods are public goods, publicly paid for, but consumers of these public goods can allocate their contribution according to their preferences (and so influence the relative balance between different PGs). Right?
In such an environment, nothing’s is really bought or sold. The ‘allocation’ is symbolic and sends signals to the producers of the PGs.
This is different from the situation you described with your nice pictures: you are selling your crabs to me in return for shells. In a pragmatarian situation, there is also no saving of shells for tomorrow, but if there are real trades, we’re in a real market situation.
If, however, our purpose is to distribute the labour between two PGs (fishing crabs and spotting ships) we need to aggregate the number of shells each island dweller wants to allocate to each activity. Let’s say there are 10 dwellers, each with 5 shells to divvy up.
Assume it’s like this:
A: crabs=4, ships=1; B: c=3, s=2; C=(2,3); D=(2,3); E=(4,1); F=(2,3); G=(3,2); H=(4,1); I=(1,4); J=(5,0).
Total shells for crabs=30, total shells for ships=20. So in aggregate 60% of the labour should be spent crabbing, and 40% ship spotting.
I don’t think we can really say anything about how scarce or abundant people think crabs or ship spotting are on the basis of this.
Do you agree?
The crucial difference with the earlier discussion is that, in a non-pragmatarian environment trading can take place at any price that produces a surplus. How the surplus is divided between consumer and producer has no effect on overall utility. That is a zero-sum affair.