Mark James Boyd wrote:

I suspect gliding is much
more popular because petrol is so expensive and in some
countries one must get a scheduled "slot" to fly a plane.

I am deeply shocked to read this statement on r.a.s.! Soaring is popular
here because it's a challenge and it's fun, while flying straight and
level with the help of a fuel to noise converter is just plain boring.

Don't the flight levels start at 6000 in some places too?
Do you need radios for this?

You're confusing flight levels with controlled airspace. Maybe it's the
same in USA, but not here.

Perhaps someone could tell us what radio requirements

All our glider have radio. Not because it's required, but because it's
a) convenient
b) safe (on tow as well as on approach)
c) allows team flying
d) is required for cloud flying

That it allows to enter controlled airspace is a nice side effect.

Stefan