> In my world, you generate a single purpose card number for each subscription, or block the company at the bank level.

You know this isn't a legal way to terminate a contractual agreement with a company, right?

You would presumably notify the company about the cancellation, wouldn't you. Unprofessional not to do so. However the ability of a company to not accept cancellation sent by, say, email, is not possible without the government acting to enforce such restrictions.

> You would presumably notify the company about the cancellation, wouldn't you

No, also not a legal method to terminate a contract.

Government shouldn't enforce contract law, got it. Sounds like utopia.