But Twitch has a latency as low as 3 seconds. Youtube, meaning the non-tv website, has latency as low as 5 seconds on some livestreams.
Twitch and YouTube live streams aren't passing through as many hops on its way to your screen. Live sports first go through a production center on-site, and sometimes even a second production truck. Then feeds are distributed to a content network (which often includes a satellite hop) from which the broadcasters get their feed. All of these things take time. YouTube TV is just another broadcaster and needs to get their feed from the same place as everybody else.