It doesnt.
These people dont go to work but they will get paid once shutdown ends, right?
Government employees are guaranteed back pay so unless they're a paychecklet with no savings it doesn't make much difference, and if your credit is so bad you also can't get loans with guaranteed income on the governments payroll you got other problems.
Contractors don't have such a guarantee but they always get back pay too, its just not codified. It can still cause work stoppage and no pay, so it does matter to them.