> A commodity is produced in the middle of a large desert. All of its
> consumers are on the periphery. I cannot see the grounds for
> maintaining a distinction between the labour that gets the commodities
> as far as the factory gate, and that which takes it the rest of the
> way to the retail outlets for the consumers to purchase.
>
This confuses transport which is necessary to production with
labour which is involved in changing the ownership of goods.
Transport is productive, the labour of advertising, posting
prices on things and collecting payment unproductive. The first
is an aspect of production, the second category is a juridical operation
required to maintain property rights.
> My worry is about the labour of trade, transportation, distribution
> and finance that facilitates commodity circulation (in a sense not
> dissimilar than that in which the labour that produced the commodity
> as product 'facilitates' its circulation as a commodity), and takes
> place under capitalist relations of production.
>
Examination of the national income accounts will show quite clearly
that the banking sector runs at a net loss on its trading account,
hence the labour of its employees is not productive of surplus value
even on a liberal interpretation of bank charges as being payments
for a 'commodity'.
The labour of the banking sector is mainly paid for out of interest
payments which are clearly a deduction from surplus value.