Flygor, on all of our aircraft the call button is in the o/head panel and pax still manage to hit it 'by accident', it's difficult to judge. Sometimes after landing pax have caught the call button while disembarking but how can the crew respond to that call when 50-60 of the pax on board are stood in the aisle, without climbing over seats and passengers. If you imagine that calls could be for medical reasons the first thing you have to consider is danger to yourself. 100ft off the runway there is an element of danger to yourself. Crew must always consider their own safety first.