Going over to your friend's house when you're a kid can be incredibly eye-opening. It's easy to believe the delusion that all of your buddies have similar relationships with their parents until you get in the car with their mom, and they start saying, "yes ma'am" to everything she says. Or worse, if your friend starts yelling at their mom in the car and their mom just sits there and takes it.
It can be easy to look at other families with rose-colored glasses, especially when you're only around them for a short period of time. If they have fewer rules than your parents or a cushier lifestyle, it can be easy for kids to think that they'd prefer living under their care. One mother whose niece stayed at her house for a month shared her story on Reddit after her sister-in-law got angry about her daughter claiming she'd rather live with her aunt.