Is it worth pursuing a career anymore...

[Troll]

It's not 10% either way, it's 10% over, 0% under.

For some strange reason, most people take the mention of an allowed leeway in speedometer accuracy to be equivalent to an allowed transgression in actual speed.

If your speedo was only ever 10% over then there would not be an issue as your recorded speed of 33 would actually equate to 30mph and therefore legal

However if your speedo was 10% under then your indicated 30mph would actually be 33 - or have I missed your point?

I suppose the simple answer would be a traffic management system to auto limit car speeds to 30 mph within a zone -radio signal to cars ECU and of course limiting all cars by law to a maximum speed of 70mph - justifiable on the grounds of 1: Safety & 2:Emissions -I wonder why that’s not on the statute books ?