There is a smelly Rort that the TAB's use when they are caught up with Losing Wagers.

What TAB does when the approximate dividend for a Place mathematically works out to less than $1 , they are compelled by legislation to pay the Minimum Dividend of $1 or $1.04 , instead of finding the Extra Money from their Profits , they take it out of the place payouts from the other runners.

Perhaps Betfair could do something similar by introducing a Rule that whenever the 1.5% Turnover Commision exceeds the 5% Profit Commision on a single Wager , some Safety Rule kicks in.