Not much different than what is currently offered through Home Depot (except made your credit card number won't be hacked).
Ratings. Uber has totally overthrown the cab industry because of ratings. Drivers are generally good because they have to maintain 4.7 out of 5 on a customer rating to stay in good standing with uber. Now think how many bad contractors there are.
A reliable third-party rating system gives you at least a minimum amount of accountability.