Because there are Banks that oppose the existence of Bitcoin and they also consider the Crypto currency is a threat to them, so it is unlikely that it happened
But if banks will shift their fiat banking system to the Bitcoin banking system then any Bitcoin banking services will become possible.
Particularly when the government will accept Bitcoin as a legitimate currency, then maybe the Bank will also start depositing Bitcoin, because Bitcoin will get a very legal status, and that will be the needs of everyone.
We hope that in the future, when Bitcoin will become more common, and more and more people will start using Bitcoin.