Two points: first, there's an inherently unequal balance of power in the employment relationship, and it favors the employer. This has been recognized going back to Adam Smith if not before, quote from
An Inquiry into the Nature and Causes of the Wealth of Nations below.
Second: the "right" to a job (or not) exists (or doesn't) because that's how the relationship's been defined in law. Law to which, again, employers have an unequal access vis a vis employees. And such relationships aren't recognized in other contexts. If you bring a child into the world, you cannot shirk your obligations to that child (unless you ensure, through adoption, etc., that they're otherwise met). It's quite possible to envision a regime in which employers do assume a responsibility for their employees.
On Smith:
"What are the common wages of labour, depends everywhere upon the contract usually made between those two parties, whose interests are by no means the same. The workmen desire to get as much, the masters to give as little, as possible. The former are disposed to combine in order to raise, the latter in order to lower, the wages of labour.
"It is not, however, difficult to foresee which of the two parties must, upon all ordinary occasions, have the advantage in the dispute, and force the other into a compliance with their terms. The masters, being fewer in number, can combine much more easily: and the law, besides, authorises, or at least does not prohibit, their combinations, while it prohibits those of the workmen. We have no acts of parliament against combining to lower the price of work, but many against combining to raise it. In all such disputes, the masters can hold out much longer. A landlord, a farmer, a master manufacturer, or merchant, though they did not employ a single workman, could generally live a year or two upon the stocks, which they have already acquired. Many workmen could not subsist a week, few could subsist a month, and scarce any a year, without employment. In the long run, the workman may be as necessary to his master as his master is to him; but the necessity is not so immediate.
"We rarely hear, it has been said, of the combinations of masters, though frequently of those of workmen. But whoever imagines, upon this account, that masters rarely combine, is as ignorant of the world as of the subject. Masters are always and everywhere in a sort of tacit, but constant and uniform, combination, not to raise the wages of labour above their actual rate. To violate this combination is everywhere a most unpopular action, and a sort of reproach to a master among his neighbours and equals."
Book I, Chapter IV, "Of the Wages of Labour"
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