What method would you suggest that hasn’t already been tried? They can’t be bribed (lotto,) they can’t be reasoned with, and we have made it as hassle free as possible. The rabbit has rejected the carrot and you think any stick is too cruel yet it’s wrong just to allow them to die. This is not a thought experiment, this is the real world and any solution will be messy, either start selectively restricting their freedom, forcibly vaccinate, or watch them die. Each solution has its problems, and like it or not it’s clear the most politically expedient one is let them die, and we have a history in this country of always choosing the most politically expedient option.