I wondered too, whether she was septic tank or city waste. I'm not exactly certain, but I thought the rules were a little more lenient in some of the outer rural/suburban developments in that area. If the city/county had not run waste pipes through an area, you would have to get a septic tank. The health dept issues the permits and they have to be a certain size in relation to home space and/or bathrooms(?). There were many developers started building, then went bankrupt when the market fell. A lot of the intended developments, never got developed, fully.
Here in S.E. Fl, imo, better to have septic tank. If you're on city sewage, they charge you 3 times your water bill for your refuse bill. Also, when everything floods, in some areas, the sewage comes back up through the pipes, into your toilet, shower, home. YUK!