I fly 400k miles a year and am always amazed when I hear snotty comments about it. With three daughters whom traveled internationally, I don’t even notice the crying.
Sometimes when I’m out (anywhere) it’s hard not to notice. A lot of parents just ignore their baby/toddler when it’s crying, thrust me it gets very annoying quickly. Trust me, I have seen adults go on talking like nothing was wrong and the baby is screaming bloody murder there beside them. When a parent is at least trying it helps, it is common courtesy and others around are less to pass judgement.