Exactly. I just realized exactly the same. There is no external dependencies in runtime. I think author should add this is as a one of the biggest benefits/features. Congratulations on delivery.
I agree. The dertiest work you can handle, that nobody else want to touch, the more you will get paid. Plumbers are good examples. They also fix problems in category of "emergency" which deserves even bigger buck. It also worth mentioning that the time for get to the client should also be included in profitability calculations. Sadly it's not a service that we could deliver over the internet.