A driver's license is to prove that you have fulfilled the "regulation" requirements the state imposes for driving, in other words that you took the test, and you have paid the "tax," as well.
You are not prohibited from driving without a license. If you do drive without a license and get caught, you are only going to be fined for not participating in the "regulation" process.
Otherwise, if driving is "prohibited" without a license then each driver would have to prove to "officials" possession of a valid license before starting their auto.
Read this if you're interested in the subject of licensing. I'm not holding my breath, 1 out of 1000 has the attention span required.
http://taor.agitator.dynip.com/on_law.htm
I'm too busy to argue with self-appointed experts talking through their hats.