Amazon opened on Tuesday its first full-size cashierless grocery store, dubbed "Amazon Go Grocery," in Seattle's trendy Capitol Hill neighborhood. At 10,400 square feet, it's comparable in size to a Trader Joe's and substantially larger than the two-dozen other Amazon Go locations, which are more like a 7-11 in scale. Shoppers use an app to scan items as they put them in the cart, and the app automatically bills the purchase to their Amazon account when they leave the store — no checkout needed.

"I think what we're trying to do here — and with all of our physical stores — is really work backwards from the customer and deliver some differentiation," Cameron Janes, vice president of Amazon's physical retail division, told CNBC. This is at best half-true, of course. Whatever their other reasons, retailers are interested in cashierless stores because they have lower operating expenses long-term.

But Janes' comment expresses one half of corporate America's increasingly dualistic approach to customer service: Customers want genuinely personal, even intimate service. And customers want to be left entirely alone.

At first glance, these seem like opposing theories, but taken together, I suspect they offer a preview of the diverging future of customer service — and suggest an unnoticed opportunity that could benefit service workers and customers alike.

There's a scene in The Office in which Robert California, the company's strange new CEO, explains why, after eight seasons of Dunder Mifflin perpetually finding itself on the brink of bankruptcy and layoffs, the paper company remains profitable in a paperless world. "Let me tell you how I buy something these days," he says. "I know what I want. I go on the internet. I get the best price. Or I don't know what I want, and I go to a small store that can help me. ... You'll find that customers [who want personal service] will pay our higher prices, and then they will thank us."

This is basically how I buy things these days, too. Online or at a big box store, the level of customer service provided is almost never more useful than the service I can provide myself. This is not a knock on service workers: Target doesn't train its employees to be able to provide recommendations on which shampoo is best, nor would it really make sense to do so. It's faster and easier for me to make this decision myself. The most significant information employees can give me is directions to the products I want, but even that's newly available in apps which can reliably guide me to the exact right aisle. When it's time to pay, I always choose self-checkout if I can; it's faster, and an awkward interaction with a perfect stranger adds nothing to my experience.

Amazon Go merely takes that model one to its logical next step, and at least some of Amazon's competitors are likely to follow. But then there's the other lane of customer service, in which intensely personalized service attention is a signifier of luxury.

Online subscription companies lure new customers with questionnaires that promise to tailor your subscription to your unique needs and personality. Personal styling services like Stitch Fix and Trunk Club tout how each customer is paired with a single stylist, someone who will read your self-description, browse your social media accounts, and truly develop a sense of your life and taste before choosing clothes to sell you. At high-end hotels and restaurants, the service is as much a selling point as the rooms or food. Your dedicated concierge will know your name, remember your quirky preferences, and develop inside jokes with you. You'll pay a higher price for that human connection, and then you will thank them.

There could be a third way: Personal service doesn't have to be a luxury if you scale down. At a big box store, it's impossible to get to know the cashiers. But in little stores, even in cities, a basic public acquaintance is possible if you always see the same three or four people across the counter. A bodega owner can recognize his regulars. When I was a video store customer, the family who ran it weren't my friends, but talking to them was part of the store's appeal. Those brief chats with someone you know a little can improve the shopping experience — they give a hit of dopamine — in a way checking out with a bored, anonymous clerk never will.

If companies are willing to hire a limited number of full-time service employees (instead of a long roster of interchangeable part-timers) to work in smaller shops that offer a limited set of products or serve a limited geographic area (like the Amazon Go convenience stores), the appeal of personal service can outweigh the convenience of automatization in a way it never again will in larger stores. Starbucks could be a model here: With regular shifts and customer schedules, you can get to know your barista, and she might memorize your usual order.

On this small scale, service is enjoyable not because it's intimately adapted to my preferences or gives me access to specialist knowledge. It's enjoyable because it's a nice, normal human connection which shouldn't be a luxury good. The value is inherent in talking to another person, not in their being able to do something special for me.

Absent an embrace of that third way, I expect we'll see the no-service and luxury-service tracks of customer experience veer ever further apart. At least when buying from the large corporations that dominate our retail market, eventually those who can't afford to pay extra for human service won't get any at all.