Are drive thrus the ultimate in laziness?

I'm amazed at how many times i go into a fast food restaurant to see that the drive thru is packed and the dining room is empty. Worse yet, there are plenty of parking spots so it's not like it wouldn't take a lot of effort to park the car and run in to get your food take away.

So what's the deal, do we use the drive thru because we want to save time, or do we do it to save energy. Ours.

I use to live within walking distance of a Taco Bell when I was younger and much more reckless. My friend and I went to make a "border run" and we walked over and the dining room was closed. So we walked up to the drive thru and tried to place an order. The attendant said he couldn't serve us since the only way to get an order in the drive thru was to be in a car. Go figure.