It's my understanding that those postal codes are or will be, changed to rectify that. People buy in Ventana Lakes believing they can use the RCSC facilities. Perfect example of bad realters.
When the VL homes were new I thought they had an agreement with RCSC for use of golf courses. Now they have an agreement with SCW under a program called Controlled Neighborhood Play (CNP).
When my parents bought a house in Ventana Lakes almost 20 years ago, they were told then the zip code would change to reflect not being a part of the community of Sun City. When my Aunt purchased there, she was told the same thing. Once again, I went to the USPS website that lists pending zip code changes and find nothing for Peoria/Sun City redistricting for this zip code change.