Yes, I think we'll have continued difficulty reconciling this understanding.

It's almost impossible to get arrested for posting something that isn't CSAM or literal state secrets on Twitter in the US. Even so-called "hate speech" is broadly protected in the US by the First Amendment. In fact the American Civil Liberties Union (which is loathed by the American right) has gone to bat and litigated on behalf of the KKK of all organizations, for example, to protect those rights.

If you send "menacing" notes to someone, that can be a part of a larger crime like harassment, assault or stalking, but as noted in the chain, that's not what's being measured here.

So the fact that people are being arrested at all for tweets is not "what I consider to be acceptable speech" but in fact what the US generally considers to be protected speech. Any number above 0 that doesn't reference child porn is infinitely more than you'd expect to see in the US. That's the difficulty we're having.

[Edit: I understand US != UK. The American flag only flies in the embassy here. I just wanted to provide the context of those arrests and these numbers to US readers who will find them surprising.]

My wife in the USA had semi-anonymous texts send to her personal over a course of 2 years. They included her home address, her mother's home address with a picture of the home, and they stated that they would kill her and anyone she loved.

She never saw justice for it. The police said there was nothing they could do, despite having the phone number it came from, because it was across state lines.

The texts stop, and we suspect that it coincided with a specific person who went to jail for a year or so for unrelated offences around the time that the texts stopped.

That person is still out there.