Different states have different rules, dealer plates are a little different, those are not tied to a vin (so a dealer can have 100 cars and 10 plates and move the plates for test drives, no paperwork needed).
As for occupation, the HAM radio plates are somewhat intended for emergency response, as in a disaster it makes these people easy to identify (and they can contact people with the phones down), their plates are their FCC license ID (so you can read their plate and then ask for them over the radio), and I know Texas let’s them register multiple cars with the same plates. The same can be said about doctor plates, and here in NY they were used during weather shutdowns, they banned the public from the streets, but those with doctor or nurse plates were automatically allowed and it also functioned as a parking permit.
The rest are mostly just to advertise your occupation, I’m an engineer, you can get Engineer plates, mostly just to say you passed the PE exam (which is difficult), CPAs have the same option, it really just shows off you have a state certification. Then there are a whole bunch of others, like military plates, veteran plates, etc. Mostly just to show off what you did really, and the state usually charges then a few bucks extra for the privilege
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