That's up to each road owner to decide. Maybe you have to pay a monthly fee. Maybe you have to have an RFID chip on your bumper. Maybe you have to blow into a breathalizer before getting on the road. Maybe you have to agree to be publicly executed if you are caught driving drunk. It will be up to the road owners but since they are trying to attract customers, you can bet it won't be too restrictive or too relaxed. Whoever can provide the safest, cheapest and overall best roads will attract more customers and drive the others out of business.
As I stated a few posts back, imagine the joy of staying current with each road owner's differing set of policies, regulations, requirements, monitoring equipment, contracts, and so on. Imagine how much fun it would be to research the different policies and fees, and staying abreast of changes due to change in ownership, and so on. You too can live the libertarian dream.