It is based on the fact that the sum of the budget deficit, the capital inflow to finance the trade deficit, and the difference between domestic saving and domestic investment equals zero.
The ability to deliver the work on the part of the employer disappears because the critical difference between an ordinary employment contract and a zero hours contract is the legal concept mentioned earlier of "mutuality of obligation".
Even this matters: with the economy currently close to zero growth (second-quarter GDP figures will be released on July 25th) tiny changes make a big difference to headlines and political fortunes.
But as we continue to add suppliers then the difference between this many but not infinite number of suppliers and the model of perfect competition moves asymptotically to zero.
Since this would have amounted to direct losses to the banks that lent the money, the difference was smoothed over by "securitizing" the new loans against US Treasury bonds, which carry a zero interest rate and are totally safe.