I have never asked for a doggie bag when I've been over at someone's house. I would feel very awkward saying "Those potatoes were great, can you box me up so to go?", I would gleefully ask for the reciepie for the potatoes and if offered to take some home I'd gladly accept.
Food is big my family. If two or more shall gather...there shall be food. At least a little nosh. There is food offered when you meet up to go out to dinner, a snack before leaving anyone? And if you come over for dinner, you are fed until you cannot be fed anymore, then you're given leftovers to last you for the next several lunches and dinners. When we moved Partner in we hired movers (cause it was summer and I didn't feel like doing it), the movers once done moving were given bottles of water (we'd been handing them water all day), some cookies and bag of chips each. I believe I offered sandwiches as well, but they declined. However if you asked my grandma for a to go order she'd calmly look at you and say "Honey, this ain't Applebees, I don't do to-go orders". If you don't ask, you get a bag of food on your way out.
I've had a few very, very, very, very close friends ask me quietly if they might take a few cookies for the road. I'll pretty much always say yes. Cause when I make cookies I make cookies to end world hunger. I also had one friend, after he'd finished eating look at me and say "So, what can I take home?", I just smiled and told him "Your winning personality", he knew well enough to know the offer of some leftovers was likely, but the assumption upset me.