Something like what you suggest is a possibility if we let tech take control of our lives to that degree. The phone idea is unlikely because one could have a phone in their possession that belongs to someone else (or no device at all) and it's probably unlikely that the government will have authority to withdraw money  directly from your account. If everyone is required to have a chip implant then a fine could be assessed using that information. Your suggestion does highlight some of the worrying ramifications that may occur as a result of the self-driving car and how technology will impose itself into our lives if we are not careful.