Point A government's sets bitcoin bann not because they know what bitcoin is and what the bitcoin is, the government is told what it is bitcoin and so on but the government keeps claiming bitcoin as a threat to banking.
Point B government claims bitcoin as a tool to launder money.
Point C government see unstable prices
Just opinion
Well the main reason for the government that they want to ban bitcoin is that they are scared of what it can do to their country. It does not have any tax when the transaction was made and done by bitcoin. Banks are just nothing while bitcoin is being used. It does not need any middleman in their transaction so that it will be a great threat for them.