Blagger, you are absolutely right. There are many examples of thoughtless glider pilots intruding thoughtlessly in power circuits; as Leon J points out, both disciplines suffer from the undisciplined.
I blush to remember when I flew a glider on the upwind side of a parachute site during a competition; and had to apologise to the entire congregation at briefing the following morning. And got fined all the points for that day as well.