Is cable video over IP now? Last time I looked (which was forever ago), even switched video was atsc with a bit of messaging for the cable box to ask what channel to tune to, and to keep the stream alive. TV over teleco systems seems to be highly multicast, so kind of similar, headend only has to send the content once, in a single bitrate.

Not really the same as an IP service live stream where the distribution point is sending out one copy per viewer and participating in bitrate adaptation.

AFAIK, Netflix hasn't publicly described how they do live events, but I think it's safe to assume they have some amount of onsite production that outputs the master feed for archiving and live transcoding for the different bitrate targets (that part may be onsite, or at a broadcast center or something cloudy), and then goes to a distribution network. I'd imagine their broadcast center/or onsite processing feeds to a limited number of highly connected nodes that feed to most of their CDN nodes; maybe more layers. And then clients stream from the CDN nodes. Nobody would stream an event like this direct from the event; you've got to have something to increase capacity.