Prior to smart meters, ours were read once a month. The meter reader had to trudge from house to house--they're about 40 meters apart on my road, although it's twice that from my house to the one to the south. Multiply that by 155 million customers in the U.S. It adds up.
There are other advantages for the consumer and for the power company. I can find out what I'm drawing in much more detail, so I can see how much it costs to run various appliances. The power company has implemented time-of-day pricing, now that it has that information.