Generally speaking police do not have permission to enter private property unless they are reason to believe a law has been broken. This is why you can ask the police to leave your property at any time. Also, many times police can not write citation on private property, they would like to believe they can but it not always true. Some time towns and cities write ordinances which give police special permission to issue citations on private properly like mall parking lots and the such and even your own property depending on the violation.
Before you can decide if the police are doing something wrong you need to first find out if the community you live in invited them in, which could be the case, I bet you someone who has an issue has invited the police in to address the problem. If they were not invited you need to check with the town to see if they have special ordinance which might have been put in place when the community was originally approved by the town.
If either of these two are true than you can probably ask them to leave and stop ticketing people, also anyone who got a ticket mostly likely has a pretty good defense to has ticket dismissed since the police were outside their jurisdiction. If you read most states vehicle code it defines the jurisdiction of these code as being public road either controlled by the state or local government.
However, before you ask them to leave and to the Senior Judges point, you might not want to cause a problem between the police and the community.