1) it's not a true shutdown because the military still get paid. There is a builtin rightwing fudge of what gets deemed "essential".
2) Most governments have a similar possibility of not being able to pass a budget; but, in the Westminster system, this forces fresh elections. The people get to decide on what compromise is necessary to resume business.
3) Businesses should not make their employees into creditors. Failing to make payroll is usually a sign that a business is either unethical or nearly bankrupt. This screws over people badly, e.g. https://twitter.com/shawndgoldman/status/1085733207469891585
"The NASA Postdoctoral Program contract runs out of money tomorrow. This means its fellows - some of the best and brightest space scientists in the world - will go without pay starting Friday. These folks are contractors, which means they aren't covered by the backpay bill."
(There was also some suggestion that not being paid would automatically terminate their J-1 visas, but I can't find that now)