The wage contract is not identical or commensurate in the sense that the labour it ‘represents’ is or can be identical to the exchange it governs.
It is an asymmetrical contract, or else there would be no gain for the employer. It is a legal contract, which renders the Tocquevillian distinction between law (superstructure) and economics (structure) somewhat void, yet it can be more or less informal though it remains a contract enforceable by law. But it is always, from the perspective of the employer, a form of accounting.
The specific elements of its taxonomic machinery (its categories, what is included and what is not) have always been a terrain of conflict, have changed, and will continue to do so — hence, among other things, the developing metrics and expanding definitions of value of service work, affective labour and zero-hour contracts.
Some excerpts below the fold from Contract & Contagion, underlining the ways in which service work (and indeed its expansion as well as contraction or re-privatisation, its relative rates of pay and conditions, its gendered and racialised composition, etc) refers to ‘surplus’ and ‘necessary labour,’ and where neither are defined restrictively as a proportion of the wage contract, but as those elements that are ‘surplus’ or ‘necessary’ to the reproduction of wages.
Regarding the wage as an accounting mechanism, Henry Ford’s significant innovation was to include the heteronormative and–nominally white or at least assimilatable–family in the individual firm’s accounting system under the heading of the wage contract (cf. “Oikopolitics, and Storms,” The Global South, Volume 3, Number 1, Spring 2009, pp. 66-82.)
That is, surplus labour is not (only) a question of production (as if there were some natural distinction between manufacturing and service work or as if reproduction were an ahistorical euphemism for gender, women or sexuality), but of the reproduction of the wage contract, in its socially contested and amplified senses.
The law of value, moreover, is therefore not reducible to issues of measure (as the debate between Negri and Caffentzis some time ago suggested), but instead is a matter of the the law (or conventions) of the household. The political question of value is answered by the form of accounting, including whether particular kinds of work are counted as work, or not.
Marx’s draft chapter on a “falling general rate of profit” begins with the division of time between “necessary labour” and “surplus labour.” Surplus labour is that portion of time which is surplus to “the reproduction of … wages.” […] Is there another way to think about the “falling general rate of profit” [beyond the limited senses in which both Marx and various marxists have assumed] before and beyond its industrial form, without acquiescing to teleological necessity, biological foundationalism or, for that matter, technological determinism?
In the Grundrisse, Marx linked the “countervailing tendency” to, among other things, the naturalisation of surplus value. […]
[…] from the middle of the 1960s, economists in the United States had begun to doubt that it was possible to easily map a Fordist, manufacturing diagram of production and reproduction into emerging markets and on the basis of a shifting foundations of the household. Becker redefined the household as simultaneously consumer and producer of, above all, services. […]
In political-economy, the household is the social (albeit often-naturalised) convention that formulates the question about the cost of the reproduction of labour-power. In the neoclassical terms of Becker’s argument, and in the debates over unpaid domestic labour of the 1960s-70s, the question was, explicitly, about whether and how to measure this cost, because while there was disagreement about whether domestic work should be paid, it was nevertheless increasingly seen by most as work.
Becker was pondering the allocation of time devoted to the “non-working time” of service work in the home, less than five years after four male black students ignored the refusal of service at the food counter at Woolworths in Greensboro, North Carolina in 1960, and in the wake of the emergence of the civil rights movement. For [Becker] the economist, then, and as might be expected, the aim was to delineate between paid and unpaid service work, situated outside and within the household, at a time when the the rate of productivity was declining in the service industry.
The allocation of a bigger proportion of service labour to the household, according to Becker, eradicated the inefficiencies of queueing. His essay, published in 1965, suggested that “the allocation and efficiency of non-working time may now be more important to economic welfare than that of working time.” “At the heart of the theory” of the allocation of time, he went on to say, “is an assumption that households are producers as well as consumers.” The productivity of the service industry, therefore, could be increased by allocating a larger proportion of service work to the “non-working [ie., unpaid and unmeasured] time” of the household.
Addendum: For an interesting take on on the ground organising in the service industry, see Shay Enxuga, “Queer Struggles are Class Struggles.”