While there is something of an official definition of DPC, I think it goes beyond that but ultimately, like obscenity, "I know it when I see it." But that makes it a bit tricky to all agree on something because not everyone sees it the same (kind of like how my mom thinks "crap" is a bad word...)
The official definition is:
1) Charge a periodic fee
2) Not bill any third parties on a fee for service basis
3) Any per visit charge must be less than the monthly equivalent of the periodic fee
But I don't think that captures the full essence of DPC. If I charged $500 a month and $500 per visit, I'd technically be a DPC practice...but I don't think I could call myself one in good conscience.
The reality is that most DPC practices cater to the needs of "normal people"...but who we define as normal varies a little bit. I am at the lower income end (normal in my practice is working class folks who make just a little too much to qualify for Medicaid and too little to be able to afford healthcare). And I have friends who are at the upper end (normal for them might be upper middle class professionals). But as far as I know, none of us cater to someone who is looking for a "concierge". But this is fuzzy...I know that at $40 a month and no charge per visit, mine is definitely DPC and not concierge. And I think $500 a month and $500 a visit would be concierge. But what about $150 a month and $100 a visit?
The statistics about DPC give something of an idea. Prices range from $40-100 a month generally. Most people don't charge a visit fee.
But it's not just about cost. It's also about what else we do. Most of us "specialize" in people who are paying out of pocket. So we help people get affordable medication (either by dispensing directly or by looking up prices on something like GoodRx. We know the most affordable place for a cash pay x-ray or cash pay echocardiogram. We are available (at least by phone) on evenings and weekends to try to avoid urgent care or ER bills for our folks. We often enjoy macgyvering...after all, DPC is something of a macgyver itself.
I'm curious how others would refine the definition of DPC?