I lived in the US for more than 2 years and so far I have a lot of friends who showed singapore passport and driving license and didn't pay for the fines. They even have court summon letters delivered. But when coming back, there's no problem.
US government departments functions quite differently from Singapore's. They are not well connected at all and seldom even talk to each other. Not to mention the police that gives you speeding tickets are not even federal police, just police acting on behalf of a small county. Usually when they see a foreign passport, they know the chances of getting you to pay up is so low they will just let you go on the spot. Having you arrested at the airport for traffic fines is basically impossible. They are not even going to bother unless you are some major criminal.
Yes just don't get caught again in that county or one may end going to sit in the police station and be getting a bigger fine.
Some states such as Washington over 30 mpg means go in and enjoy a free meal at the police station. One time they let u go, happen again same trip might bring one in and you can pay with your credit card on the spot.
in cities like Chicago or New York City, don't pay basic parking violation next time kena risk getting wheel lock or veh tolled. My pal kena lock b4 thinking can Siam since over 1 yr ago. End up paying over 10x the amount.
I met students from Malaysia years ago knowing they wouldn't return to USA run up debts on all possible credit cards. Return rich buying jewelry spending over $20k.
Perhaps they get this! Wouldnt get arrested even coming back. Not suggesting it's right..
http://money.stackexchange.com/questions/28530/defaulting-on-credit-cards-before-leaving-the-country