It's the ownership that's important. You can consider scalping a specific form of the generalized issue of doing something outside of an agreement of something

It's the ownership that's important. You can consider scalping a specific form of the generalized issue of doing something outside of an agreement of something you don't own, e.g. subletting a room on Airbnb if a rental agreement forbids it. If you own a phone (or some other object), unless there is a law that specifically forbids some action, at least in the US you are able to do whatever you want with it, because you're not renting the right to use the phone, you are the owner of the phone. That's why in this case, it's not fair that Google turns off service for purchasing a phone and then selling it to someone else (a reseller in this case) because they person who purchased the phone is now the owner and selling their phone to another entity is not against the law. In fact, there are laws that specifically allow this.