With increased civilization comes increased specialization. A lot of people become crucially important. You see this when they strike, which people love to do around here. We do have laws that can stop strikes when they endanger life and health. But we don't have laws that can stop virus. If we get a pandemic even the size of the Spanish Flu of 1918, we could be unlucky and lose clusters of key personnel, causing disproportionate damage to society.
We need to have backups for various functions, and we need to pay people to have knowledge they hopefully will never need.