"Legal constraint" (to labour) "is attended with too much trouble, violence, and noise, ... whereas hunger is not only a peaceable, silent, unremitted pressure, but as the most natural motive to industry and labour, it calls forth the most powerful exertions."
Human beings have basic needs whose fulfillment lays the foundation for everything else they do. If a person wants to write a book, they need enough confidence to know that the energy they put toward their work isn't going to put their family in jeopardy because they aren't selling that portion of their vitality to an employer for the maximum wage on offer.
Men were then forced to work because they were slaves of others; men are now forced to work because they are the slaves of their necessities.1
The world is still organized in a fashion which compels some people to work for others. Wherever such compulsion is unable to threaten us on the grounds of explicit starvation, it works tirelessly at broadening our conception of what our "necessities" really are, so that we feel we "can't live without" an ever-increasing number of things -- whether they are articles of convenience or the adornments of status and reputation.
Where capitalism begins by withholding the means of life from anyone disinclined to work on its behalf, the struggle between classes alters this relation over time. Anywhere capital is hemmed in by the progressive impulse of humanity toward life and freedom, it changes shape. By the 1950s, C.L.R. James contends that capital's consolidation within the organs of the state was a worldwide trend reflecting the options available to it at the time, which found their expression in the governmental models of Stalin and FDR. Since the 1970s, capital has been freed from the constraints of the national economy, so the role of the state has been pushed back, along with those compromises capital accepted in an earlier era.
What this means for the US is the convergence of increased insecurity vis-a-vis those "rights" won through struggles of the past -- the "end" of retirement, social security "reform," etc. -- with the unabated creation of "new necessities" in the form of disposable amusements requiring constant devotion. If our attentions are monopolized by chasing after our new necessities, it will be much easier to erode the long-established "necessities" of an earlier time -- the eight-hour day, to name just one of these already endangered species.