I didn't say "Radar contact" means you are under positive radar control.
Those things shouldn't get mixed up. "Radar contact" means your position has been
identified on a radar scope. It doesn't mean you are under radar control.
I'm saying that, outside the UK, you know which service to expect because you know which class of airspace you are in.
e.g. when flying VFR in G, there is no separation provided but avoidance advice is available on request. Previous radar identification will make it simple for us to anticipate on such situations. Thank you mode S...
In class C you'll be separated from IFR traffic, flight info on other VFR traffic, etc...etc...