Trying to fill your stomach ASAP
The trick here is that they want you to be full as fast as you can. They serve high-calorie foods first before they serve those that have less. This is the reason why you have rice, noodles, fries, mashed potatoes, and other high-calorie foods at the start line. Some even claim that eating too much is bad and therefore call themselves an “all you care to eat” buffet.
This is not a coincidence. They even resize your plate to smaller ones to make you think twice about getting back the line for more. Moreover, the high priced meals are usually crowded with cheap ones. Some cheap food might even look tastier. They do not put all the expensive food out in one go. This will make your conscience shame you for taking other people’s share.