"Regulatory Doc Fee" seems to be a renaming of the inspection and prep fee.
In short, this seems to be the fee for doing all the state-mandated paperwork stuff -- registration, title, mandatory safety inspection. They shouldn't have renamed it, because New York has legal limits on what you can charge for that. (sigh). Combining it with the destination fee as a single fee probably avoids that problem though.
Now, if you have your car drop-shipped to Texas, have to take it to an inspection shop yourself, have to register it yourself, etc., then this really is a complete cheat. Apparently they're charging this to everyone, even when they're not providing the "regulatory document" services.
Since they're charging it to everyone they should just make it part of the base price of the car. Tesla's been real big on advertising bogus prices. I didn't fall for any of the phony price ads -- I knew what it was going to total to early -- but it's just *shady behavior*.