Apple and oranges. Most any insurance premium would also cover the child's medications, hospitalization, cancer treatment, etc. in addition to primary care.
Also,
that $10/month for the child is based on at least one adult parent paying $50/month, as well. So, figure $60/month for two people. That's $720/year.
A typical healthy adult and healthy child would probably not pay that much in insurance co-pays for a couple of routine office visits per year apiece (the average), even if the adult had a physical with basic labs. By definition, AtlasMD's patients are a self-selected population who feel that he's providing them good value.If they didn't, they wouldn't be his patients. And, lots of people aren't his patients.
Don't forget that most patients are (or should be) paying for high-deductible catastrophic insurance coverage on top of whatever they're paying you out-of-pocket for primary care.