Banks are not countries. Banks are not states.
Bolivia did not ban bitcoins. Bolivia's banks did.
Nevada, New Mexico, Arizona, etc. are not warning against using bitcoins. Their banks are.
Saying that a country bans bitcoins when their main banks ban them is like saying that a country has banned Whoppers because McDonalds in that country has banned all Whopper sales in their restaurants.
News alert, banks do not transfer bitcoins. Banks do not hold bitcoins in their accounts. Banning their use in their banks is meaningless.
bigger newsflash , Banks are more involved with Governance then people imagine. One can be used to exercise the will of the other, and often happens. But hey, you are right, they can't "write" into law their own stuff, but their lobbyists can. and if you can't use the technology at the FIAT point of exchange, you are handicapping the convenience, and therefore the adoption by users.