Dollar General has shut down self-checkout at a whooping 12,000 stores in the last few months. Here's why.

• Dollar General removed self-checkout from more than half of its stores this spring.
• The retailer has struggled with theft and other forms of lost inventory.

Dollar General's rollback of self-checkout picked up steam this spring.

The retailer cut self-checkout from 12,000 of its 20,000 stores, CEO Todd Vasos said during an earnings call late last month. Dollar General ended self-checkout at 3,000 stores in May alone, he said.

"Moving forward, we plan to have self-checkout options available in a limited number of stores, most of which are higher-volume and low-shrink locations," Vasos said. "Shrink" is a metric that includes losses from theft as well as other sources, such as inventory that is damaged and has to be written off.

Dollar General's shift away from self-checkout has been dramatic. In March, the company said it offered that option at 14,000 of its stores.

Back then, the retailer said it planned to eliminate self-checkout from just 300 stores and convert thousands more to a model that directed customers first to a staffed checkout, only using self-checkout when foot traffic increased.

Dollar General's crackdown is part of its plan to reduce inventory losses, including from shoplifting.

"Shrink continues to be the most significant headwind in our business," Vasos said on the latest earnings call. Besides rolling back self-checkout, Dollar General is reducing the amount of inventory shops have on hand — overstocked stores have been an issue for the retailer in the past.

It's not the only retailer that's changed course on self-checkout lately. Earlier this year, Target started limiting self-checkout operating hours at some of its stores, for example.

Walmart also pulled self-checkout lanes and added human cashiers at a few stores in New Mexico last year.

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