Aw... that was so sad about the poor girl getting yelled at and smacked by her mother, even though she'd done the right thing in asking a CM for help!
We managed to misplace our daughter once in the Main Street shops when she was nine. She'd plopped herself down on the floor behind a stack of shelves to read, and no one could see her, not even the CMs who were helping me look. She was off in another universe, and never realized we were all searching for her! After 20 minutes or so, she stood up and looked around, saw me going past, and went, "Hi, Mom!"
I was justifiably ticked off. But it still never would have occurred to me to yell at her or smack her. We just did the "we're very disappointed in you" thing, and that was enough. And I made a mental note to keep a closer eye on her in the future.
My son also got lost when he was ten, with a 9yo friend. They'd gotten off the ride, and couldn't find their friend's dad. My son searched briefly, then flagged down a CM, who started the "walk around the area" routine and in short order they were all together. No one was mad, in fact I got a call from the dad that night praising my son for his clear thinking and maturity. Which is the way it should be!