I feel it has more to do with the ability to hire a competent attorney. As in every other profession, attorneys can be divided into a multitude of categories, but suffice to say that there are great, good, average, below average and just crappy attorneys. Also, as with everything else, you get what you pay for. If a person has to get a court appointed attorney, they are getting the bottom of the barrel most of time because those are the attorneys that either just passed the bar, have no experience and haven't built a client base yet, or they're getting an attorney that can't build a client base because they're an awful attorney but still have to make a living.
Basically, it costs a minimum of $10,000.00 to hire an attorney to go to court for anything other than a basic traffic violation. The price goes up as the level of the accused crime goes up in severity. This is why a lot of people plead out, instead of going to court for a full trial, and also why many will opt for a judge instead of a jury trial. The cost of paying an attorney to go through sitting a jury can add a lot to the bill, but it's worth it if you have a great attorney and can afford it (see story at the end).
So, I don't think that rich people get treated differently, as much as they can afford to pay for competent and highly qualified representation. It's like getting your car fixed at the dealership or by the guy down the street that was on TV a few weeks ago for doing crappy work. Both places have mechanics - the dealership is more expensive, but you get what you pay for. Another example would be eating at a restaurant that had a highly trained and very popular chef, versus the greasy spoon or fast food restaurant that has a minimum wage cook. Both places will give you food - the chef's food is more expensive, but is probably more healthy for you to eat and tastes great, where the minimum wage cook's food is probably cheap, fattening, may make you sick, and may not taste good at all.
An attorney that has a good or great reputation has that for a reason and you have to pay for that. It has to do with his/her intelligence and their ability to use the law, rules and procedures in favor of their client. An attorney that's getting what equates to "lawyer minimum wage" is probably not the person that's going to be able to use the law and precedence or the rules to help get their client a fair and positive outcome in a trial.
So again, I don't think that any judge or jury is going to say to themselves that "Hey, this guy is rich so we should let him off", although that may happen in some cases - 'OJ Simpson' - but even his case had more to do with his great attorneys than his celebrity.
A lawyer buddy of mine told me a lawyer joke:
A sheriff's deputy stopped by a friend's farm one day. He saw the tractor in front of the barn still running and no one around, but the barn door was open. Feeling something bad had happened to his friend, he got out of his patrol car and walked in the barn to check. When he walked in, he saw his friend with a goat's rear end against him and his friends pants down. The deputy told his friend that even though they were friends, he would have to take him to jail but would get him a great lawyer.
The farmer hired the lawyer, and when the lawyer visited the farmer in jail, he told him that he thought the best thing to do was to get a jury trial, because the lawyer had a great reputation of getting the best jurors for his clients problems.
When they went to court, after the lawyer had picked the best jurors, the trial began. The deputy took the stand and told exactly what he had witnessed. The prosecution rested and the defense called only one witness... the farmer. When the farmer took the stand, his attorney said "Just tell us in your own words, what happened." The farmer said, "Well? I was out plowing in the field and had to pee. I looked around and saw that my neighbor's wife was in her yard hanging up the laundry, so I couldn't just get off the tractor to relieve myself. I had to drive the tractor to the house. When I got next to the barn, I couldn't hold it anymore. I jumped out of the tractor, left it running (as the deputy had testified that he saw) and ran into the barn to pee. I dropped my pants, and before I knew what had happened, that goat had backed right up on me right when the deputy walked in..."
At that point, one juror leaned over to another juror and said... "You know? A good goat'll do that."
This story shows, that a great lawyer can get you off (no pun intended) for just about anything.