That's pretty paranoid of you. You are forgetting a crucial fact in this matter. Pirates. Data is never taken down for good. A trace always exists. With piracy, censored/deleted materials can live on.
Think for a moment. Who is the most likely to be anti-government, and want to expose and spread ideas they might ban? It's the same people who provide you with your warez and assorted media copies. These are the people that run wikileaks. Anti-government, socialist, anarchists. Your books are safe.
It really all comes down to one question. Does government censoring actually work? No, especially not in this day and age. Look at China, Iran, North Korea, Egypt, Syria, etc. The people get the info. They get the outside connections. There is no stopping the internet.
Take off your tin foil hat and come out of the basement.
You give pirates too much credit. Not something I would have expected from someone who on the other hand has insisted pretty much all criminals who are in prison deserve to be there, and that prison conditions should be as harsh as possible.
True there will always be pirates and bootleggers, but the grand age of internet piracy (or internet privacy, depending on how you look at it) is over.
As of the first of last month all of the major ISPs in the US agreed to monitor their users for suspicious activity, such as using torrents, and are implementing a graduated response system to scare most of them away and prosecute those who persist. I don't care how hardcore an anarchist is, throw them in jail for a few years and take all of their possessions then tell them if they ever get on the internet again you'll put them back, and they're probably going to live a life less connected. The government already does these internetless conditions for sex offenders who are released so not only are such restrictions possible, they're already being done. I think it's only a matter of time until such restrictions are placed on persistent internet pirates, it's a logical next step.
What's more the FBI now has the IP addresses of all the people who ever uploaded or downloaded anything on megaupload, so there's a few million people they can scare away from ever pirating again right off the bat, and a lot of people who will be going to prison/sued for all their worth as well. No doubt it's a similar story for the recently shuttered torrent site Demonoid. Once the millions of casual pirates are gone governments can do serious damage to the hardcore crowed who weren't initially scared away.
And besides, if the government or amazon wants to keep people from seeing something, I'M not going to risk anything to see it, most people won't. You don't need to completely destroy something for censorship to work, just make it so most people don't have access. Or alter it so the version most people see is the one you want them to. And with digital media they can find the people who do get access to restricted content so bonus for the powers that be. Not to mention if there were something like a revolution in a powerful country the internet could be shut off completely, though that's not likely to happen unless it was an extremely powerful country.
And please, do we really need to bring out the tinfoil hat bit again? Amazon has the power to pull anything they want, all they need is an excuse, they've done it before. With unauthorized editions of 1984 and Animal Farm, of all things.
http://www.nytimes.com/2009/07/18/technology/companies/18amazon.html