The AP does not in fact call who wins. They publish their opinion, some people trust the AP to be accurate (or not!). The election is only "called" when all the states have certified their results and the US Congress has accepted those certifications. That happens early in the new year.
Polymarket had each state at above 95% likelihood of trump well ahead of the networks suggesting he was winning each state. It’s not just calling winner, it’s ingesting information faster