Where did the restaurant customers go?

McDonald’s, Starbucks, Chipotle and Dunkin’ Donuts have found themselves with something in common.

Their established U.S. stores saw fewer customer visits in the latest quarter. All reported higher sales at locations open at least a year. But that was because they raised prices and promoted more expensive items or sides.

Investors see customer visits as a key indicator of a chain’s popularity. But when there are so many options, it can be difficult to get people visiting more often. So instead, chains drive up sales by squeezing more money from those who do come through their doors. Of course, they have to be careful not to drive people away by hiking prices too much.

In highly competitive regions like the United States, being able to walk that line is a challenge for many big companies. Smaller chains can struggle too. Shake Shack, which has about 180 locations, also saw sales increase at established locations, even though traffic declined.

It’s not a problem just for restaurants chains. Companies that make soda or cereal may employ similar strategies as their products lose market share to newer alternatives.