More seriously: Almost all cars in Germany are limited to 250km/h (155 mph). Higher limits for more powerful cars are also found in the 280-290 km/h (173-180 mph) range.
So, de facto, even in Germany speed limiters have been a thing for decades. The discussion should thus be more about the limit, rather than the device itself.
Obviously this is different than imposing a „+10 mph“ limit, since the car would have to know the speed limit of the current road.
As a German, I have to fiercely object to people fiercely objecting here. I would enjoy German highways way more, if there was a sensible speed limit just like there is in the rest of the world. Also, I think the police should start going after people who don't keep safe distances (as a function of the speed they're going) and pressing criminal charges for intimidation.
On a public road, not in most countries. But racetracks are a thing, and regular people do go there, in regular cars.
Most cars do have electronic speed limiters today, which are often set to values that reflect the mechanical limitations of the vehicle (e.g. the designed speed rating on the factory equipped tires, etc)
Sometimes I go over 100 on I-70 in rural Colorado/Utah after Grand Junction when there's a huge straight road and you can see for 20 miles and there's no one around
Alot of cars do have a governor limiting the top speed, 115 and 155 are common. This is mostly because you need to look at every part of the car to know that is could go that fast. Car manufacturers limit it so the tires won't blow out for example.
It's better than nothing and no one should ever go at that speed anyway.