Marx's argument is in Capital, that prices will reflect the fluctuating value component, as expressed in
average productivity socially necessary labour expended in their production.
So it isn't an exact model: if domestic servants value
productivity differs from (say) video game programmers, the price of the commodities they contribute to won't express the actual number of human hours of labour, but only the number of hours of human labour that our society (through market, production, class war) deems
socially average.