That depends on where those bytes go, though. There is also the concept of “settlement-free peering” and content caches that are located in the ISP network.
For example we have a Google Global Cache instance in our network, so most Google traffic is served from there and we don’t pay anyone per byte, we only pay for the power and space. Same for Akamai. Then for Microsoft, Cloudflare and Facebook we have peering links, where we can send and receive data related to their services freely, without balance requirements.
Of course this is only possible for larger networks (peering with everyone is not feasible) and we still pay for the other traffic, but it takes care of a lot of the volume.