[chatmasta]

Market dynamics are subtly different than statistics of traditional polls, since you need to account for fees and slippage and irrationality. You’d also need to compare this to a poll asking “who do you think will win the election?” which is a different question from “who are you voting for?”

[n2d4]

"Subtly different"? It's not even remotely the same thing, all they have in common is that the unit is %. The betting probability is the (expected) chance that a certain candidate wins, while polls measure the % of population that votes for a candidate. A polling lead of 20% would seal the election.