Plumber's job with a single customer usually lasts one or two days, so the plumber's income is not dependent on any single customer. They might be willing to ri

Plumber's job with a single customer usually lasts one or two days, so the plumber's income is not dependent on any single customer. They might be willing to risk it and take a job without a price set beforehand, because the worst case scenario they lose, say, a single day pay.