It seems to me in all 3 accidents, the Cabri in UK, the 412 in Spain & this now, that the airplane approached and hit from above and behind in all three cases. It is a almost impossible situation to see and avoid a target coming from that direction.
Someone mentioned a increase in inflight incursion or nearmiss. One has to wonder if the increase of electronic devices are part of the reason. It can hardly be due to more traffic since private flying is on the decline.