The less information available, the more likelihood that the winner will be at Over The Odds.

In your Top Quality races, the Form is well known to all Punters, and The Punters that bet on those races know a aaaa of a lot more than you and me.

Its strange that we tend to pick a higher proportion of winners in Quality Events than we do in Maiden Races, but the Winning Prices in Maidens are higher.
I don't know if thats true.
I just made it up.

But if someone has ever run a database and added up all Prices of winners grouped into better Races and Poorer Races I would think the poorer Races would throw higher average Prices.