Most people are always in a hurry and are running behind schedule which means such inconveniences as the speed limits are rarely paid attention to. For many people, if they're not driving 10 mph above the posted speed limit, they're about to be run over by other traffic. That has to be accounted for by the current models of driverless vehicles. If they can't go above and beyond current speed limits, they could actually cause accidents.
With those parameters in mind, Google has given "permission" for their driverless vehicles to exceed most speed limits by up to 10mph. Regardless of the legality of the issue, the rationality is sound since driverless vehicles currently have to work within the "system" that exists. That means not only do they have to obey the rules of the road, account for other vehicles in the system, but they also have to account for human actions. In the case of exceeding the speed limit, if the driverless vehicles don't exceed the speed limit, they could be responsible for more problems than they're trying to solve.
We're not in a place where humans are ready to give over complete responsibility of a vehicle to computers. We're not in a place where humans are able to accept the fact we're not as capable of accepting the fact that computers are more capable than we are. That means car manufacturers and computer software manufacturers will have to cope with the "human" factor when designing new vehicles that rely more on computers and less on humans for control. In the future, it may be possible to have every vehicle going the same speed. But, for today, that isn't going to happen. And, to keep people safe, having driverless vehicles that exceed posted speed limits is not just a necessity, but only makes good sense.
What type of new objectives will this present in your business? Will the cars take themselves to be serviced? How would a driverless vehicle be ticketed by an officer for "exceeding the speed limit"?