Because in non-legalise common English usage, "fine" just means "financial (usually) penalty for wrongdoing".
A civil lawsuit doesn't need to be anything like a speeding ticket from a legal point of view, from a normal person's point of view they can both result in a "you did something wrong, now you have to pay an amount set by the legal system".
Yes, people make mistakes, especially when common usage of a word like "fine" doesn't align precisely with legal use. In my opinion it's getting upset about not everyone having a concrete understanding of the legal system that there's no need for.
Where's the discontinuity, they just assume everything that happens in court is the result of actions by the gov't when it's not just true. I don't get your tone, as if people making mistakes is a concept I'm not familiar with. That's not what I'm discussing, I'm discussing widely made mistaken assumptions from an otherwise incredulous crowd.