Sure the total of all available services will be high, but you will still have the choice of only subscribing to the ones that you want. If someone only wants Netflix, it's still only 8$ per month.
Furthermore, there's currently no contracts keeping you on a service. Say you wanted to watch Season 1 of Agents of S.H.I.E.L.D. on Netflix. You sign up, watch it in a month, and then decide that nothing else in the inventory matches your tastes. You could cancel your subscription until Season 2 is released. Total cost for watching the one season of the one show could be as low as $8.99.
Last I checked, Netflix will also let you "pause" your subscription - incurring no monthly fees, but also not giving you access to their library - for awhile. I'm not sure if you could pause for 10-11 months and unpause for 1-2 months, but if you could this might be preferable to signing up/cancelling repeatedly.
Amazon is a bit different since they ask for $99 a year. This makes "watch one season and then cancel until the next one is released" trickier. Still, you can always cancel your subscription if you don't feel that the library of content merits the cost. It's a lot easier to cancel one component of the online video services you subscribe to in order to reduce what you pay a month than it is to ditch unwatched cable TV channels to reduce your monthly cable TV bill.