I think gliding has powerful friends because gliding has always been a part of the military services, and in all of the world the aviation regulators are drawn from the military - even more strongly so outside w. Europe where most countries are de facto run by the military.
Also, gliding does not generate any great emotions because it is a purely hobby activity, done purely (well... usually) OCAS, and this sidesteps any airspace issues.
As soon as you get to normal GA, you have airspace entry issues and the usual vested interests crawl out of the woodwork.
When you get to IFR GA (airways) you get the absolute business in elitist behaviour on the part of the regulators.