Why do people seem so offended to wash hands?

Literally anytime I ask someone to was their hands before holding my infant son, they roll their eyes and seems offended. I mean, the other day my FIL used the bathroom and didn’t wash his hands and grabbed my son out of my husbands arms before I could say anything!! Like it takes 30 seconds to wash them. Basic hygiene people. I mean, how shitty would you feel if you’re the reason a baby got so sick it had to be admitted to a hospital?