A good example is SiriusXM. They give you a lowball initial offer, and the fine print says that at the end of the offer period the subscription will automatically renew at "then current" rates. To cancel you have to call their 800 number (which of course will put you on hold long enough to make you give up.)
MasterCard is making an awesome first step here. The next step is to insist that companies must let you cancel subscriptions online, just like this California law: https://www.cnet.com/news/companies-must-let-customers-cance...