Everything isn't on it. That is why some people are more loyal to one streaming company over another. We've been happy with Netflix, but we don't tend to watch a lot of the HBO series. We actually like a lot of BBC stuff. Movies and TV---and there is plenty of it to see with Netflix. Some is streaming, some is DVD/Blu-ray.
I thought you could see what was offered before you signed up though. Didn't you look?
Also, I am pretty sure it is 2 weeks free trial... is that what you signed up for? If so, check it out and cancel it if you decide it isn't for you. No harm, no foul.
If you are looking for a particular program/show/series, then you need to be sure to do that research before making assumptions about watching it on a particular provider. I'm pretty sure that all of them cycle shows, and don't continuously and continually show the same seasons of the same series for ever and ever and ever. They move on and get newer or different material. Something gets dropped. Perhaps they'll pick it up again later, perhaps not... you don't really know. But for $8 a month or so, it might be worth it for other things to watch besides the one you were looking for. You never know.
We found Luther just browsing drama. It's a fabulous show. Idris Elba. :D