Even information that we get for free on the internet is not truly free. Economists point out that nothing is truly free. They say that "there is no such thing as a free lunch." That is true of material on the internet as well.
At the very least, everything has an opportunity cost. If I spend time editing Wikipedia pages, that information may seem as if it is free. However, I have essentially paid for it by taking on the opportunity cost of having made it. I gave up things that I could have been doing with my time in order to create that content.
With regard to the internet, things that we think are free are not free in other ways as well. If we pirate a film or song, for example, we get it for free. However, there were certainly costs associated with the making of those things. If the people who made them cannot get compensated adequately for their time and effort (due to piracy or other factors) they will simply stop making those works. The works are not free and when we treat them as if they were free we risk losing them as people stop making them.
No it is not truly free because there are some implicit agreements regulating the fair use of some kind of “free” resources on internet.