Not at all, they are everywhere. Some times, like during morning and evening rush hour, right turn filter arrows will be set to turn on and off periodically, allowing traffic to go right over a busy road.
During non rush hour the filter will be switched off and is triggered by pressure pads underneath the surface which a car will need to drive on to register its need to turn right. The arrow will, via the miracle of telemetry, be triggered for a brief spell, stopping on coming traffic at the same time. This also means the traffic coming the other way isn't stopped when there is nothing waiting to cross.
If the driver does not drive onto the pressure pad it will not trigger the arrow and they could be sat there for quite some time.
Standard.