Comcast is issuing routers that are also open wireless access points for other Comcast customers. If you live in an apartment complex or near enough to another

Comcast is issuing routers that are also open wireless access points for other Comcast customers. If you live in an apartment complex or near enough to another house, what's to stop said youngster from just connecting to some other access point? Of just tethering his phone, if you're a relatively rich family?