Depends on what's meant by a special district. These are not all that unusual anywhere in the United States. RCID was unique in that it took over for the operations of what would typically be run by cities and/or counties including fire, public safety (although they contracted out policing to the counties), sewage, utilities, public works (like road construction/repair), building inspection/permits, etc. And it was really interesting with Bay Lake and Lake Buena Vista, which were nominally cities but seemed to have very few powers that cities would normally have.
I deal with several special districts where I live in California. They include a regional parks district, public transit districts, a public safety district, a sewer district, a water utility district, a local parks district, etc. I see references to them on my property statement for supplemental taxes. That's apparently the deal at The Villages where it multiple single-purpose special districts as opposed to the broad powers that RCID had.