that's incorrect. in practice, MasterCard cannot do any of the things you suggest, aside from "arbitrarily refuse to accept payments for a business", which they have already done. your bank could shut down your card due to fraud, which may suck for you, but you can switch banks if you disagree with them. unemployed people can absolutely get visa/mastercard debit cards. ditto homeless people.

mastercard deserves criticism, but try to actually stick to things under their control (e.g. their appalling but now discontinued ban on wikileaks donations).