I got a ticket for a U turn in California about 11 years ago. I told the female officer I was leaving for a flight that day, in a few hours and showed her my airline icket, she told me It was up to me and stay and go to court or leave for home on a plane. I threw the ticket in the bin at the airport.
I continued to travel to the USA for work about 3-4 times each year up until 2 years ago and thats that. Never heard anything about it ever again.
I was once emailed a parking fine from a rental car company in California, they wanted me to pay it, so I did.