The person operating the wireless network
What person? 90% of the time I guarantee places won't have someone dedicated to doing a person to person search to see who's using the network.
i doubt that anybody will casually [and publicly] bet $2000 in a pub. even so, if you were to bet that amount of money, why would you go around telling people about it so you can get arrested?
Just connecting to my routers administration panel gives me a list of all devices connected to it.
That said, in non-pubs, I find it difficult to comprehend why such a law would exist, especially in places like Las Vegas. $2000 is small bet in many tournament games, once the blinds are raised high enough.
In a state in the US it is illegal to cross the border driving with a chicken on your head.