We are forgetting what someone already mentioned, they may have had to remove the bumper to access the winch and/or wiring in order to replace. That would drive the labor way up. You can't think in how long it takes to perform a task, it is book billable hours period.
Since you are not threading into the fairlead itself, you just need to find a matching nut and bolt of appropriate thickness. I think a 1/2" grade 8 bolt works.