Think about it: What would it take to get you to go through the hassle of switching to GEICO (or any other agency)? You would have to save a substantial sum of money. People don’t switch insurers in order to pay more!
Different insurance companies use different algorithms to determine your rates. Some weight your driving record more heavily; some put more emphasis on the number of miles you drive; some look at whether you store your car in a garage at night; others offer lower rates to students with good grades; some take into account the size of your engine; others offer a discount if you have antilock brakes and traction control. So when a driver shops around for insurance, she is looking for an insurer whose algorithms would lower her rates considerably. If she is already with the cheapest insurer for her personal situation, or if the other insurers are only a little cheaper, she is unlikely to switch. The only people who switch are those who will save big by doing so. And this is how all of the insurers can claim that those who switch to their policies save a substantial sum of money.
This is a classic example of selection bias.
