breastfeeding children that aren't yours

I keep seeing on Facebook a woman breastfeed a baby while the mother was in surgery or women donated breast milk to help a baby of a fallen officer. Don't get me wrong that's nice and all but am I the only one who finds that weird? I'm not bashing the women who do this but to me I find that weird to do. I wouldn't want my baby to drink a strangers breast milk or suck on another women's breast.. they have formula and bottles that a baby could eat from.