Though Comcast doesn't bill by bytes used, they do put a monthly cap on the data usage, and charge as much as $100.00 extra per month if you bust the cap more than once per year. Details here.

Their 1.2TB cap is dangerously low. We are in a household with four work-from-home adults who have a lot of Zoom calls, and we do a lot of video streaming for entertainment. We hit the monthly cap last December when I got a new game console (a bunch of new game downloads), and everyone was doing video calls with their families in addition to their jobs. So now I have several months in which that can't happen again without incurring their extra fee.

So even though I'm not "billed by the byte", I've been given incentive to keep a close eye on my bandwidth usage.