Politicians might not be able to get out of being convicted for federal crimes, but they might be the first in line for the new iPhone, for example. This small favors are seen as taking care of politicians and allowing them to do their job, rather than worrying about the small things.
I feel it is obvious that politicians are treated with preference. That said their preferential treatment is no different from the advantages bestowed upon anyone at all considered famous or a celebrity. Why it is that the average American considers these human beings to be some type of Gods will be an eternal question.
Politicians still receive preferential treatment today. Congress is allowed to engage in stock market insider-trading that would land private citizens in prison. Also, many politicians are never prosecuted for crimes that would land ordinary people in legal trouble. The few politicians that do get prosecuted rarely spend any time in prison.
Winston Churchill received a prescription for alcohol when he visited the United States during prohibition. Politicians are constantly receiving preferential treatment. Tony Blair famously holidayed with George Bush and David Cameron now has a fancy multi-million pound home. Where did he get this money? Well, perks of the job of course!