Many countries use a combination of a percentage of the speed limit, and a maximum overspeed (for example 20mph) before losing the license. Hefty fines long before those limits.
Assuming you ask about the signposted speed limits, I guess making them suitable to the road conditions, but also taking into account other road users, would make sense. Especially now when drivers expect not to have to think at all, and just keep to the posted speed limit (as a lower limit) regardless of visibility, other road users, and so on.
So, yes, more nannying because drivers don't do their own assessments any more.
Also: Drivers should be forced to take a "pedestrian experience course" walking along some heavily trafficked B-roads. That should scare the sh*t out of them, and give them a valuable lesson. Might help with the obesity epidemic as well.