@browncoat - Once that might have been true, but I'm not sure if it is these days. Every time you interact with a bank or a credit card or make a purchase that isn't cash, you're leaving a trail. You can't buy anonymously online because you'd need those credit cards to do so. Bus stations and train stations have fairly comprehensive security cameras and there's only so many places you could go. And if you hitch with someone they are definitely going to remember you.
And then you've got to look at it from the side of the person who is escaping. If they are having a trial they probably still have hope they can get away without jail time. If they only did something small, they will only have to serve a few months in jail, as opposed to having to start a whole new life and never being able to contact their family or friends again.
I think people are only really a flight risk when they did something very bad or they have no one to stay for, otherwise most people would prefer to face the music than go on the lam.