Come on Wilyflier, more details would be appreciated if you're going to use that one incident from 20 years ago. What height? Designated and well known hang gliding area? Perhaps the hang glider flew over a known model aircraft strip and clubhouse that he should've read up on before taking flight?
If this all happened 20yrs ago with a responsible model aircraft flyer, I'd say short of just not flying his model that day, there was nothing else he could have done to prevent a collision with a hang glider.
Life is full of risks. A woman was killed in London by being knocked down by a cyclist with no front brakes. He was cleared recently. There's no talk of banning bikes nor banning bikes cycled by irresponsible cyclists etc and yet cyclists and pedestrians mingle many more times per day than a drone is flown up into the air.
Have you read the CAA commissioned report into Drone collisions? It's linked above. Talk about starting with your answer and working out how to get there. Vested interests are trying to shut this hobby down for, well, their own vested interests.
It's no coincidence that the US military have stated they've ordered their members to not use DJI products. Also, they will shoot down any drones they see flying close to their installations (apparently, from cyber fears that the Chinese could then hack what the pilot recorded)
This clampdown is not about safety and a Phantom hitting a 320 at 140kts.