There are lots of people paying for things they don't need or could save money by switching subscriptions on & off as needed. This is one of the reasons why the subscription model is so popular with companies, not consumers.
So I've started to subscribe/unsubscribe to channels through prime. It's really easy to subscribe/unsub. I unsubscribed from HBO when game of thrones finished.
But... lots of things? lots of things unsubscribing is horribly painful.
A lot of things you have to call someone, listen to the sales pitch, look up a bunch of customer data you might not have anymore, and then listen to another sales pitch and then cancel.
I have started dealing with this by just canceling the credit card. (I've got one of those cards that lets me generate throw away numbers, so I don't have to cancel everything) way easier.
So, uh, my guess? my guess is that the 'subscribe to movie through amazon' is a lot less sticky than 'subscribe to channel through cable' just 'cause it's three clicks. And then another three clicks if you want to re-subscribe.