There's an expectation when it comes to consumer goods, and even protection in most jurisdictions, that you can't simply charge someone for something they don't want. It's like dropping a Mercedes at someone's house then charging them for it when they never wanted or asked for it. Allowing a "free" tier to run up so much traffic that it becomes a $100k bill is ridiculous and probably illegal.

Taxes are different because they never exceed the amount the person paying the taxes receives.