I would expect minimum-wage laws would still apply? I mean, they may be hard to enforce for short-term cash-only transactions, but that's true with other informal jobs as well: Craigslist gigs, or even the old-fashioned method of paying one of the guys standing outside Home Depot for a few hours of construction labor.

(Though an interesting question would be whether TaskRabbit makes any attempt to enforce minimum wages, or if that's the responsibility of the buyer.)

? I think this is a good idea, and I think unions and minimum wage laws are a good idea.

you appear to think there is some kind of contradiction there?