Except it's not "SHUT DOWN EVERYTHING". It's shut down all non-essential mass gatherings until we can get a handle on the situation. All of the governors who implemented strict shelter-in-place orders have also released detailed plans for re-opening safely.
Where I am (Scotland) it WAS pretty much everything. Only shops selling food, medicine, or maintenance products are allowed to open. All others have been shut for ~2 months now. Driving is strictly forbidden unless you’re travelling to one of these stores that have been ‘deemed essential’. We’re not allowed to meet anyone outside of our household, even in a socially-distanced outside context. I have friends unlucky enough to be living alone and single, and the lockdown is destroying them, to the point that they’re secretly meeting other single friends to stay sane. All of this is in spite of the fact that there are thousands of jobs and activities that can be EASILY done whilst also socially distancing. Of course, it requires vastly more thought and effort to come up with rational guidelines that take into consideration all of this nuance, and governments (mostly because of shortsightedness) haven’t had the time to create more humane lockdown solutions, hence the indiscriminate restrictions that have been brought in by countries the world over.