How self-checkout took over our favorite stores — and how it's upending the way we shop

• Self-checkout has become ubiquitous over the past few decades — as have its frustrations.
• The kiosks are usually a help for both shoppers and retailers, but there's much room for improvement.
• Here's what's changing in stores' self-service lanes.

Since the introduction of self-checkout more than 30 years ago, the technology has become ubiquitous in stores across the US and around the world.

But as the benefits of the tech have spread in the form of speedier service and higher sales, so have its frustrations, like technical errors for shoppers or rising rates of missing inventory for retailers.

In recent years — and especially within the past several months — retailers like Walmart, Costco, and many more have been rolling out new tech and strategies to adjust to evolving challenges in the self-service lanes.

Walmart is leaning big into its redesigned checkout zones, which replace traditional lanes with a staffed corral of kiosks where shoppers can opt to scan and pay on their own or have a worker do it for them.

Costco meanwhile, which relies on membership fees for most of its profit, has cracked down on shoppers allowing non-members to use their cards at self-checkout registers.

Other retailers are seeking new ways to curb losses, which can rise by 31% to 60% following the installation of self-checkout machines, or otherwise bring back a more human touch to an increasingly lonely world.

Meanwhile, those anti-shoplifting measures are frustrating some customers who say they are fed up with systems flagging them as potential criminals.

Here's how retailers are reimagining their self-checkout strategies.

Walmart's reviews are mixed, but it's betting big on flexible hybrid checkout zones

Walmart is stripping some stores of self-checkout lanes and bringing back cashiers

Some Walmart employees say customers are getting hostile at self-checkout — and they blame anti-theft tech

Walmart shoppers say they are fed up with the store's self-checkout system

Walmart managers are going to extreme lengths to get customers to complete the retailer's checkout survey. It's confusing shoppers and workers.

I tried Walmart's self-checkout to see if it was as frustrating as some shoppers say. Here's what I found.

More than 100 Walmart stores nationwide have a new look. See 5 key changes in the $500 million redesign.

Costco wants you to show your membership card to a person before checking yourself out

Costco is asking employees to heavily monitor self-checkout at some stores — and customers are divided

Costco is cracking down Netflix-style on shoppers sharing membership cards to use at self-checkout

Costco, Lowe's, Best Buy, and Tractor Supply are winning the battle against retail theft in a strikingly similar way

Costco CFO says that only a 'really small percent' of members misuse their cards, 'but when you're dealing with millions of transactions' it adds up

Shoplifting almost always increases with self-checkout…

Walmart rolled out self-checkout to streamline operations and reduce labor needs — but employees and customers say it's causing a surge in theft

Giant Food president says thieves are stealing 'everything' from shrimp to deodorant — and warns some grocery stores could close

Some San Francisco Safeway stores added gates barring shoppers from leaving unless they scan a receipt. It's an anti-theft measure that has spread across the UK.

… and stores continue to adjust their self-service strategies.

Amazon Fresh stores are installing self-checkout after years of trying to get customers to use Just Walk Out tech

Trader Joe's executives say employees will never be replaced by self checkout and insist those chatty cashiers are not trained to flirt

Self checkout could be making Americans lonelier

Retailers appear to be facing a self-checkout reckoning

A UK supermarket chain is firing its self-checkout stations and bringing back real people as cashiers