Milk cartons and magazines are interesting examples. It really depends on the magazine and the subscriber, but speaking for myself the one type of magazine I still subscribe to is a trade magazine and I subscribe to it in part because of the ads. Yes I read the columns and the content is important, but because it's a trade magazine I'm actually curious about new products and the magazine is a completely opt-in way to get that information delivered to me. I can unsubscribe at any time.
Milk cartons are disposable packaging so who cares?
My phone lock screen though? I don't much like the idea that some remote server somewhere can push something in my face in a way that I can't choose to ignore it, throw it away, opt out .. and, oh yeah, it's on something I paid hundreds of dollars for.
I think that's the difference.