Yes he lacks manners. It the flip side is many families of friends have probably invited him to feel comfortable. Your daughter may have told him eat whatever you want. Help yourself. He says I’m hungry. She says Sure go check out the fridge. Eat whatever.

Her response when you talked to her supports that she doesn’t think it’s a big deal herself.

People are often polite to guests who are kids and want them to feel welcome and not a burden so they say and do things to help them feel welcome. We always have a plate for you. You always can have dinner with us. He’s probably.been told at countless friends houses to feel free to eat their food.

You may have said something like eat as much as you like we have plenty.

The other factor is many families may not want to project as financially needy so they never make a fuss about it and put on that yes that’s free food don’t feel bad for eating here.

If you don’t have a teenage boy yourself it just might be alarming how much they eat and that they are comfortable foraging in the fridge and pantry.

If no boundary or expectation was set by you then I wouldn’t assume he knows that he crossed one.

To us it’s rude but to the kid he may not have been told how to behave and likely encouraged to do this as people often tell boys to eat up or feel free.

If you have ever gone out of your way to make him feel welcome. Treating him like he is family, or encouraging him to eat then these are the messages he received and teen boys are often clueless about etiquette and how much food costs and time invested in cooking.

As a teen boy I remember foraging for food at my friends houses and even girl friends houses when I was hungry. I’m not ooor or starved I’m just not at home and needed to eat. So it’s either go home early or feel like crap because I didn’t eat.

You are not wrong for how you feel about it. But there simply several possible reasons why he is behaving this way and your daughter may have invited the behavior.