This isn't entirely true. Rural properties have septic tanks that are maintenance free for years at a time. The waste is digested by bacteria in the tank and effluents runs off into a septic field. The tank is pumped out only when there is a substantial amount of undigested sludge filling the tank.
Depending pn usage, septic tanks can sometimes go 20 years before being pumped. My house has heavy usage (lots of people), so it gets pumped every 2 years or so. It could maybe go longer, but it's not worth risking it getting over-filled.
