Presumably, one of the main draws of living in a gated community is safety and security. You pay a premium to live in a place that selectively lets in vehicles.
But really, a determined thief or murderer is not going to be deterred by a horizontal bar across the entrance - all it does is stop their vehicle. This may be enough to deter the casual miscreant, but it also has the down side of potentially stopping people you might want to admit to the community, too.
Today, as we were driving home, we ended up distantly following an ambulance, moving fast with sirens screaming, towards our neighborhood. Next to our (open) neighborhood is a gated community, and the ambulance turned into the short drive and raced up to the gate. We could see it turn from a few blocks back, and by the time we passed it and turned into our own subdivision, it was still sitting at the gatehouse, lights spinning, unable to enter. Impotent. Apparently, the gatehouse is unmanned, with the big metal bar controlled by a computer and card-reader. Presumably, the ambulance driver was trying to get a phone number so someone could buzz them in, but in that wasted time dealing with the "security" system, what was happening to the person for whom the ambulance had been called?
It seems to me that the gated community is not charging for security, but rather a sense of security. That big metal bar won't be effective at keeping out someone who wants to kill you, but it will keep out the people who come to save you from him. If their system cannot distinguish between a crook and an emergency vehicle (because they're too cheap to hire a person to sit in the gatehouse), then they're basically charging you a premium to make you less safe.