I use it to verify a person's claimed height.You have two options:
1. Be a creepy weirdo and scan someone's height without their knowledge.
2. You can ask the person (who I would hope is either friend or family) how tall they are.
In the 80s kids were notorious in claiming their "WWF" height... in other words being 1-2 inches taller than they actually are.
Also... the measure does not compensate for the thickness of the person's footwear.