A lot of cars already have speed limited fitted. You can set them to any speed you like and overrde the setting by flooring the accelerator.. I don’t see anything other than mandating their inclusion in cars built after 2022. This is not about having to use them!
Yes, our last half a dozen cars have had this feature, but you have to activate it yourself and I rarely do, other than perhaps a long stretch of motorway roadworks with a 50mph limit where the traffic is too heavy to use cruise control. I had rather assumed (probably incorrectly) that the suggestion was that this would be configured to operate by default automatically based upon speed limits (detected by the Sat Nav and an in car camera, as many cars already have both these features, so the technology exists). If so, that’s a game changer and raises a lot of safety issues but I’ve probably misunderstood.