Because they have ALWAYS received their back pay when the furlough ends.
Past furloughs have been the consequence of Congress and the Executive Branch not producing an Annual operating budget on time, resulting with no legitimate authority to pay government employees.
Different games were played to keep essential services alive, but generally the authority to hire employees rests upon the authority of Congress to approve the budget authorizing the Executive Branch to pay the bills.
When they were late, and employees were furloughed because of the late budget approval, the politicians quickly approved some form of payment to those who had relied on Congress meeting their timelines. Congress found it simpler to just pay the normal pay than to further account the issue.
The present situation is different.
By Law, if the budget isn’t balanced to a certain degree, then automatic cuts are forced on governmental agencies.
To some extent, the services are deciding how to distribute those cuts.
In DoD, the emphasis is mission accomplishment, and DoD is able to furlough civilians up to 22 days without forcing a RIF. That’s why they are issuing the furloughs.
Believe me, even the flag ranks haven’t fully thought through the consequences.
FWIW, in contract services and MILCON alone, there is a strong likelihood that the costs the government from this furlough will be 3-5x greater over the next 5 years in contract claims, equitable adjustments, undocumented work, and poor quality uninspected work. It will also slow down maintenance and repair work, with many utilities tottering on loss of functionality.
Worse, there will likely continue into next year more furloughs, RIF, early outs, and loss of corporate knowledge. Training costs and logistics costs will escalate.
More badwill than goodwill evolves from this evolution. Lots of quality employees will leave the workforce, while the less qualified will strengthen their unionized positions.
The military operational costs are also severe.
Up till now we haven’t really seen the enemy operating in our own back yards. Add that into the mix, with domestic enemies competing with foreign enemies, and it’s going to be a new century for our little nation.