Companies are trying. The Wendy's by me has an "AI" ordering process in the drive through. Consequently, I don't go to Wendy's any more because I hate talking to the clanker. But I imagine a lot of people just do it.
The rest of your comment suggests tney have yet to fully succeed.
McDonalds tried for 3 years. They found that roughly one in five orders required human intervention. AI created bigger problems than it solved --- like driving away customers.
Now at first brush, while I don't think that AI could replace fast food workers, McDonald's obviously also went Hard Mode when they partnered with IBM to provide the AI.