Define low cost. Higer cost CGs are no more safe than lower cost CGs. You really can't go by site cost.
That being said. I have never stayed in a unsafe CG in NC. No matter what cost. I have stayed in some that were not as nice as others, but not unsafe.
Ebenezer Park, a York County park in Rock Hill, SC is about 12 miles south of Charlotte.
A real gem, it's 26 acres on Lake Wylie, nestled in an area with expensive homes. A first come, first served park, it's popular with the locals and difficult to find a spot during the camping season, especially on the weekends. This time of year, you should not have any problems if arriving early in the week. From 4/1 to 10/1, there is a 14 day stay limit at which time you must leave the park for 24 hours. For the rest of the year, it's unlimited stay but you have to move to another section of the park every 14 days.
It's gated with a keypad, FHUs 30 or 50amp, plus WiFi (works most of the time) for $15/night for non county residents and $10/night for seniors, age 60 and above. Comfort stations are clean and heated during the winter. Grocery and shopping within 4 1/2 miles.
We have stayed in places where there was a wooden RR-type gate which was "supposed" to keep out non-campers in the park. Half the time the gate was broken .. and began to wonder if we were keeping the "bad guys" in or out ?
We consider the amount of traffic in front of the park and how open the campground is as to whether we feel "safe" or not.
Safe is a relative term. Are we safe from loose dogs, un-disciplined children, intoxicated campers next to us, or ? Just exactly what do you mean by Safe?