Wow it looks like Prudie's response hit way to close to home with some of you all.
Yes, parents should certainly have the right to have adult activities separate from the children. But if your idea of 'adult activities' includes going out and getting plastered on a regular basis, only to stumble in at the wee hours of the morning, I'm going to bet that you are too immature to be a really good parent.
No, the kid isn't going to be up at 4 am to see Mommy stumble in. But Mommy is certainly going to still be drunk off her ass when kiddo wakes up at 7 am. So right there kiddo gets a lesson that being drunk is more important for Mommy than being there for him in the morning.
Then there is the whole 'oh once in a while doesn't hurt!'. Yep, I agree. If Mom wants to get drunk off her ass once a year then it isn't going to do the kid any lasting harm. But the letter sure doesn't sound that way to me. In fact, according to the LW, Mom was doing it 100% of the time that she had the opportunity. Sounds like a problem to me.
Oh and as for the straw man of 'nobody would care if it was the Dad!' - I don't see a single comment that supports that. Personally I think it is just as bad of a problem with Dad as Mom. But nice attempt at trying to distract from Mom's actual behavior.