Wage garnishment happens at the end of a long series of legal filings and claims against the debtor.
And, again, you can avoid it by changing jobs. Which is easy enough for someone in a low wage service sector that very few debt collectors bother trying.
You tend to push for wage garnishment when the person is in a job they can't easily leave - partner at a law firm, manager at a Fortune 500 company, tenured professor - not someone who can walk across the street and land a new job doing the same work at the same pay over the weekend.