First thing that comes to mind is, how would an officer know who has the speeding license and who doesn't? If he has to pull everyone over who speeds to make sure they're doing right, it would defeat the purpose of the license; would the one with the speeding license need a custom license plate? If so, how might we secure these plates so that people without proper training wouldn't steal them? Or perhaps steal them and sell them to make a profit. And even then, it's difficult to read them when you're going fast.
Perhaps a speeding-only lane would be more appropriate, where there is a minimum speed limit; maybe something like the autobahn. But I don't think that'd ever happen in America, as tickets of any sort are a great source of income for any city. Just the other day I paid off a ticket of 350$ for expired inspection and failure to produce my DL, and I have no idea how expensive speeding tickets are but I'm certain they're nothing to fuck around with. When you make money by imposing a set of rules, it's hard to reason against it, even if it's better for people to not have the rule. When you're in the business of waiting for people to fuck up, you generally like to keep that business going strong, preferably by imposing as many laws as you'll get away with. Not saying something like this wouldn't be possible, but, unless there's money to be made, it's pointless.
So that would mean, if we figured out how we can get these speed licenses to work, that the classes you'd take and the fees you'd pay to get a speed license add up to, say, a year's worth of speeding tickets. To ensure this revenue, you would impose a law that stated, "You must renew your speed license yearly" or however long you want, and then charge a premium for renewing, which would be a quick and speedy process, with the added bonus of being much more expensive than is actually required to renew the license.
This brings up my idea; the speeding license has to replace all revenue from speeding tickets.
How many tickets a year does the average person get? 1 every 2 years? have people pay whatever price per year to keep the 'speeding' license and that's all the state should want; the extortion money