I have a three year old son, and I was a nanny for twenty years and I can tell you most dads just don't know. It's not that they don't care, they are just overwhelmed. Yes, some dad's know and mess stuff up so they don't have to anything again. I would tell your friend to sit and talk with her husband first of all. Ask him how it went, what she could do to help. Ask did he pinch and slapped their butts and yelled, or give him a chance to tell her what happened. Maybe she could tell them what she does when the kids, don't listen or act up, to give him an idea what to do for next time. First I would start with smaller steps, maybe only leaving one kid home or leaving only for an hour or two.
I leave a list for my husband, yes even after three years, he will still forgot to feed our son, or has no clue what to give him to eat. I try and make a simple schedule, leave snacks in containers with times to give to him, fill juice and milk cups and leave containers in the fridge of what to give him for lunch/dinner. If they are going out, I make sure everything is ready. Coat, shoes, bag. So all he has to do if put on socks, shoes and coat. I leave a small backpack out, so my son can take some of his toys with him in the car. If I won't be home at pj time I leave pjs out for him to put on.
I did this with a lot of the dad's I was a nanny for too. It seemed to help because it took the time off to think about other things that that had to do. I know no ones does it for me and I try to remember I am doing this to help, to make fun of or to yell at them why can't you do this. I did this for the mom's I nannied for too. I think we all prepare for things, packing diaper bags or getting dinner ready for the next night. Not everyone can be as great as we are : )
Good luck!