If freedom of speech is absolute, how come it's not applied for private spaces and for the Internet?

That’s what it is. You have no right to use other people’s stuff. If people let you use their stuff, they can tell you how you can use it, and they can tell you to stop using it any time they want.

Terroristic threats

Perjury

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Child pornography

Threats of violence

False advertising

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Fraud

Revenge porn

Conspiracy

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And much, much more.

HIPAA violations

Revealing classified information

Why do some people prefer watching movies than reading novels even if they are both based on the same source material (book)?

No freedom is absolute.

Insider trading

Insurrection

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You have freedom of speech. If I loan you my computer, I can tell you not to use it for certain things, because it’s mine, you have no right to use it, and if I give you permission to use it I can tell you what you can and can’t do with it.

If you’re wondering why free speech doesn’t apply to the internet, it’s because you have no right to use other people’s stuff for free.

Freedom of speech does not apply to:

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You have freedom to travel. If I loan you my car, I can tell you not to take it out of town, because it’s mine, you have no right to use it, and if I give you permission to use it I can tell you what you can and can’t do with it.

Trade secrets