The service can have a better insurance than the individual worker, etc. Ultimately it's up to the service to add enough value that you want to keep using it.

The service can have a better insurance than the individual worker, etc. Ultimately it's up to the service to add enough value that you want to keep using it. What if your favorite worker is busy? Either you have to find a replacement yourself (a failure), or the worker knows someone else who's available (and then the worker is basically running their own small time service).