When the polls calculate likely voters, I think they often count people who have voted in the last few elections. So even if they poll those people, they may be left out of the likely voter tallies.
Figuring out likely voters vs. registered voters is a secret formula in every poll. If a poll is wrong, it’s because they miscalculated that eventual turnout.
It all comes down to likability. Which candidate you would rather have show up for dinner at your house? That's the candidate that wins an election.