That's the thing - there wouldn't be much public money involved. Welcome to American sports, clubs are privately owned and operated like a business. In Oakland $2 is what you get paid an hour if you can find some casual work through a day-hire labour outfit - $2B in Vegas is just a good week at the craps table. Hence the relocation (I assume) - Oakland has one of the highest unemployment and largest proportion of the population living below the poverty line in post-WWII America. Sure, the Panthers started up there but not too many could afford either the baseball ('A's' - which used to be owned by Connie Mack, not sure who has them now) or the football ('Raiders' - which was bought by Al Davis back in the '60s, Mark's old man).
Not sure about the Vegas move, but I know that Oakland has to be one of the toughest places in America to make a buck and Vegas one of the easiest.