Sorry....my wording was a bit unclear there. I said I think the car's faster
without it on
So totally agree with you. It tends to hold you below limit which is not the fastest way round a track and it also tends falsely intervene every now and again.
Every manufacturer has different standards and expectations from ESP tuning, and the way the systems intervene is very much down to company policy/personal choice. Ultimately someone has tuned the ESP in the car to their personal interpretation of the company policy. It's a Conti ESP system and their pretty good at tuning the systems, and I think the way it comes in is very good, it's just a bit early, so I suspect VW wanted it to be seen as a 'Safety System' in the true definition of the term. It does actually actuate without the light coming on which you may not notice. Next time you're out, find a long smooth, wide sweeping corner and build the speed up gradually. Fairly early on, you can hear the ABS pump running. It sounds like a rough 'cchhhrrr' and will last for about half a second.
You're right, that if you're heavily leaning on the system on the road, the speeds are a bit much, but I tend to find it's little nudges early on a bit intrusive on a B road!
As for the supercar systems....their actually identical! It's all in the tuning
The main differences you get in more expensive modulators are more pumps which improve refinement and reduce the pedal feedback. The Conti ESP though can and does brake individual wheels and it's definitely able to request a torque cut from the engine when it's managing traction. The amount of time/effort that goes in to tuning a system is fairly incredibly considering most drivers will only ever use the function for probably a maximum of a few seconds in the cars life!