From memory, the FAA PPL includes VOR navigation, and I distinctly recall some VOR and ADF questions in the FAA PPL written exam which would have been found in the IMC Rating written exam in the UK.
However, the flying situation is different. IMHO there is a lot less call for "VMC on top" flight in the UK than in the USA.
In the UK, it's rarely that one can fly above cloud without being in CAS and usually it;s Class A. I have done it a few times, in Class G, but I don't recall a single instance when I did it (in the UK) without transiting IMC on the way up or down, so I was doing it under the IMCR or FAA IR privileges anyway.
Also, due to the scarcity of instrument approaches here, people prefer to scud run below cloud and accept the increased danger of that, over the risk of getting trapped above a layer and (assuming IMC capability now) having to do a DIY descent through cloud.
In the USA, you can fly up to 18k feet under VFR, in general, and laws of physics being similar all over
I bet that US PPLs can do an awful lot of VMC on top flying.
Elsewhere in Europe it's also more doable. I've been around Europe quite a bit under VFR and all the long legs were done VMC on top. One does end up in CAS but it isn't normally Class A and transits in the FL050-150 region are more readily given than in the UK, and are managed by the enroute/airways controllers; here it would be Class A and even if one could fly in it VFR the airways controllers would not offer you a service with a bargepole. If the UK allowed VMC on top flight (and had say Class C up to FL195 or whatever, and Class A above that) it would need to set up a whole new layer of "FIS with radar" controllers like they have in say France. Nobody is going to do that now.
I guess that local regulatory attitudes have developed in line with the local airspace...