This sounds like a money-making opportunity. If 85% of drivers insist on breaking the law, they should pay. We can then use that money to redesign the road for more traffic calming.
Drivers going 30mph in a 20mph haven't done anything wrong, the road designers have failed by making unreasonable speed limits, shown by the fact that it is ignored by 85% of people
That soudns great. But why spend that money on traffic calming? Let's just use that money to install additional speed-camera's and build more roads that encourage more speeding. Revenue generation must be priority number one for every government!