I recall hearing about Japan putting speed limiters in all cars and using GPS to determine the road and therefore speed limit to set the limiter dynamically in vehicles. (Perhaps some details are wrong or confabulated; regardless, it’s a neat idea.) I’m in favor of such a system in theory; I’d be concerned about privacy issues but there’s no reason for such a system to require driver identification anyway.
My family rented a car in England last summer, and this was an optional feature of the car. I didn't want to try it out on my first time driving on the left, so I didn't turn it on. Moreover, the speed limits on the motorways were changing in real time. I observed very little speeding -- almost none.
You’ll have been on a variable speed zone of the motorway which is covered in cameras to enforce the limit reductions. People tend to behave themselves when they think they’ll lose their toys.
If you drive in an area that’s known to not be covered by cameras, you’ll see it more, though it might be less than where you’re from.
My car has this feature and a method to read signs but it cannot read white exception signs. There are plenty of speed limits when wet signs which get cought by the thing as normal signs.
And the maps are continuously outdated so lots of smaller roads simply do not work properly.
