You could just copy others signed codes, so you would also need some sort of totp system.
Then you could still place some camera capturing and streaming plates of parked cars in real time, so you’d either need 2 way communication with the license plates, where the cameraa tell them to show a code for some specific nonce, and which you could then potentially still stream so would also need severe latency checks, or you would have to get way more reliable gps and make that part of the totp.