There are probably 2-3 of them in any major affluent suburb in the south. They are typically built into a strip center or on a pad site near one (because of the cheap land.) Most of them are emergency rooms by the letter of the law only meaning they don't have an operating theater, mri/ct machines, huge amounts of trained staff. They typically have a few stabilization tools and a nurse practitioner on staff.

Anecdotally I was sent to one by my primary care doctor because she thought I was having a heart attack as a result of month long strep/sinus infection. They gave me a bag of saline and charged me $1000 (insurance ER rate) for the privilege. I think these places exist only to bilk parents with crying children in the middle of the night and people who don't know any better.