I really hate that groups like Google and Facebook 'take over' the internet through their use of size and money. People often do not surf the net as often as they did in the late 90s which makes them more gullible and easily marketed by whatever FB and Google wants to show them.
Everyone should understand that the governments of the world control the internet. If there was something they did not want you to see it would not be on the internet. Some people only get to see what their government views as safe material in their countries.
Well technically there is the dark web that governments would like to control but cannot. I see Comstat's point which has been perpetuated by having preinstalled info that highlights these sites. For instance Android is all about Goolge and the Facebook app is already on most phones as a default.
My 2 cents worth : It all depends on where you are. In China, the Chinese government admits that they throttle, filter and control almost all aspects of their internet. The Great FireWall prevents anything the government thinks their ignorant populace shouldn't see from reaching them.
In other countries, the government control ranges from negligible(USA & Canada) to overt censorship (Iran).
Once past the government, the prime thing that controls what we see on the internet is a base impulse the human race has had since it's development of civilization - greed. Corporations don't really care about morals or ethics, once they've reached a certain size. They only care about providing profits for their stakeholders. In order for a company to survive, it must grow, and in our money-driven world this means making profits. Very few companies balance the morals of employing people and still making reasonable incomes well. In fact, most companies these days are in it to be sold to bigger companies (Little fish eaten by bigger fish, which get eaten by bigger fish, etc.). This means that companies like Google, Amazon, Facebook, etc. All develop algorithms and cultures that are geared towards getting people to pay to their never-full hunger for cash, and will do anything they can get away with to accomplish this goal. Which is why companies regularly get called on the carpet by governments and agencies when they over reach themselves. Greed drives the growth in almost all cases. Very seldom do companies of this size consider that what they should be doing is using the profits to hire more employees and give people livelihoods, rather than reduce staff sizes and make more profit. Mega corps are emotionless creatures, and shareholders are their drivers.