Is it okay to wave at kids even if they're strangers?

The Breakfast Club 09/08/2018

Lana was in a car with a friend recently. They pulled up beside another car and Lana started waving to the kid in the backseat of the car next door.

Her friend told her to stop it and even called it 'a bit weird', but Lana admits she's been doing it for years!

Is it really that odd to wave back to a child if you don't know them?