My experience (n=1) was not so bad.

I cancelled Amazon Prime 4 or 5 times in the last decade. Yes they try to keep you and make you jump through 2 or 3 confirmation pages but it never prevented me from actually cancelling on whatever day I decide to do so.

Audible also has a lengthy cancellation process and usually informs you at the end that you get to enjoy the benefits till end of current billing cycle after which you will not be charged.