In most of them there is an initial probationary trial period during which you can easily fire someone without providing any justification, and with a minimal mandatory notice.

It goes both ways: during that time, the employee too can quit with a reduced mandatory notice.

That only covers the "if that person ends up sucking" part though.

For the other "business falling apart", maybe they consider it’s part of the business owner’s responsibility to make sound business decisions when involving someone else’s livelihood. Just like when leasing a shop or taking on a loan.