Online shopping was the best thing that ever happened to UPS. Think about it: while the internet sent so many other businesses and industries scrambling to adapt, the rise of e-commerce seriously increased demand for what UPS was already doing. Amazon still needed someone to put the box at the door.

But over the years, one-click retail has fostered an even broader change in consumer expectations that's now forcing UPS to evolve as well. Just as shoppers believe they should have the power to buy anything whenever and wherever they want, they also expect to actually get their hands on the thing without hanging around the house all day waiting for a package to arrive. So, on Wednesday, UPS responded to the imperative of ultra-convenience by launching a trial run of some Amazon-style delivery lockers that let buyers pick up packages whenever it's convenient for them.

The company is operating its first lockers in metropolitan Chicago, and members of its preferred customer program, called My Choice, can have packages routed to these lockers instead of their homes. By scanning a government-issued ID or in-app barcode at the locker or entering a PIN at the touchscreen terminal, they can open the door holding their deliveries and retrieve them. Judging from photos, the lockers are big, with many doors, and yes, they're that signature shade of brown, which makes them look kind of like UPS delivery trucks without wheels.

Easier for Everyone

Along with the lockers, UPS is starting a program in both Chicago and New York City that lets customers pick up packages at local businesses, mostly grocery and convenience stores with evening and weekend hours. Ken Finnerty, vice president of customer technology at UPS, says the company was focused on creating what it calls "access points" in urban areas. Cities, he explains, are where deliveries can be the most complicated.

"Those are consumers who have challenges to overcome," Finnerty says. "If you live in a metropolitan area—say, in a multi-unit apartment building—and don't have a doorman, it becomes very difficult sometimes to receive deliveries."

But it's not just recipients who are inconvenienced by missing deliveries. Though the company is eager to push the benefits of lockers and in-store pickups for consumers, missed deliveries also create more of a logistical burden for UPS. Second and third delivery attempts mean one less spot in the truck for a new package. What's more, if the company holds that package at a UPS hub for pickup, this takes up space too, and it's not totally predictable when the recipient will come by to pick it up, if they come at all.

The Special Relationship

Lockers, on the other hand, get deliveries most of the way there. And the more packages a driver can deliver to a single location, the more efficient that driver's overall delivery route. Increased efficiency is especially important in the world of online retail, where major customers of UPS such as Amazon are making big promises on shipping times that carriers are under huge pressure to keep. The more options UPS has for getting packages to customers, the less likely it is to run into delivery logjams such as the one that brought the company's tense relationship with Amazon out into the open last Christmas.

Adding features to keep Amazon and its shoppers happy is important to UPS. But so is keeping Amazon from muscling in on the delivery business itself. The last mile is the only part of the customer relationship that Amazon doesn't control, and recently, it has ramped up efforts to deliver orders to big-city customers itself through its Prime Fresh program, which offers groceries along with thousands of other items available on Amazon.

Amazon has long offered delivery lockers of its own, but the company has had some trouble finding brick-and-mortar partners to house what amount to machines that make it easier to shop at their biggest online rival. UPS may run into less of that resistance because it's not a direct retail competitor to brick-and-mortar. People get all kinds of packages shipped for all kinds of reasons.

As a result, UPS could have an easier time as it tries to widen its logistical footprint in US cities. Getting more packages delivered to more places at more times will keep Amazon customers happy. At the same time, it would mean Amazon and just about every other online retailer would still have to rely on UPS to get those orders to customers, no matter where they wanted them, or when.