Mommy?

Why would someone’s 3 year old call every woman he sees mommy?, just curious, my friends kid calls me mommy all the time and he calls other people mommy too, I mean I have no problem being his mommy but like I wouldn’t wana crush him, I know my friend has him from 5pm -7/8am and then his mom has him but I was thinking he doesn’t have that mom roll model in his life?, I’m just curious, he’s a good kid n I jus feel bad for him 🙁 and my friend and his ex just had a little girl 3 months ago