Checkers and Carl’s Jr. are among US fast-food chains hailing AI-powered drive-thrus as labor-zapping wizards that speed up service. But a popular provider of these systems recently revealed a crucial part of how it gets so many orders right: humans.

Presto Automation Inc. pitched a restaurant industry desperate to combat rising wages on a talking chatbot that could take orders with almost no human intervention. The firm touted OpenAI’s Sam Altman as an early investor. And it has used the firm’s technology to improve its system as it aims to triple deployments to 1,200 locations next year.