My understanding is that no one used hubs anymore, so your collision domain goes from a number of machines on a hub to a dedicated channel between the switch and the machine. There obviously won’t be collisions if you’re the only one talking and you’re able to do full duplex communications without issue.
Hubs still exist(ed), but nobody implemented half-duplex or CSMA from gigabit ethernet on up (I can't remember if it was technically part of the gig-e spec or not)
