‘Not guilty’ does not mean innocent. It means only that the prosecution has failed to prove the accused’s/defendant’s guilt to the requisite standard of proof.
Not guilty absolutely does mean (legally) innocent. You can argue the toss whether legally innocent should be understood as innocence in the wider sense of course, but the point stands.
If that were true then wouldn't the concept of double jeopardy not exist?
The UK has been phasing this out..
To the downvoter. I'm sorry you don't like this (I don't either) but you can't downvote away facts.
How would you propose treating people found not guilty legally?