@Monty1 Put it in your house rules that it's mandatory that guests supply the information, or their booking will be canceled. That usually gets their attention. You would do well to explain that it's a government requirement, and that you're not just all up in their business.
Set up a timeline- like the information has to be supplied by X days before arrival, and set up an automated message as well. If they don't comply, they don't stay. If it's in your house rules, AirBnB will *usually* back you up.