McDonalds has as much authority to ban a Burger King product as a bank has to ban a competing currency.
I don't know what "authority" means in practice.
GE can get incandescent light bulbs banned because they want to sell more CFLs. Taxi cartels can get Uber and Lyft banned. Appalachian coal mining companies can get EPA regulations that flavor their dirtier coal over the cleaner Rocky Mountain coal. Child seat manufacturers are well on their way to getting driving banned if any child under 30 years old isn't sitting in one of their products. Monsanto can get seed lines that aren't Roundup Ready banned.
Do any of these companies have the authority to do this?
All that matters is whether they succeed or fail in getting what they want, and they succeed fairly often.
In each of your examples:
company -> government -> ban
In no instance can:
company -> ban
other than within their own company.
We get it. Banks have a lot of money/influence/lobbyists, etc.
But a bank cannot ban bitcoins.
Unless a bank has the power to kidnap people and put them in a cage after a socially accepted show of "fairness" they do not have the power to make something illegal. Only governments have such power.