Right, I should have said "this bet". But the same goes for any other bet with clearly erroneous odds. However, bettors choose which offered odds to bet (while

Right, I should have said "this bet". But the same goes for any other bet with clearly erroneous odds. However, bettors choose which offered odds to bet (while books accept whatever matches their 'board', within limits). And, good bettor practice is to check slips before leaving the window. Thus a bettor can in practice exercise more discretion/control, in such a situation of odds-error-against-them, than (non-managerial) window clerks. They can simply not bet at bad odds, in a way that's harder for the bookie'srote systems, and they can usually even cancel a slip printed with surprisingly bad odds, on-the-spot. So errors-in-the-houses-favor will become actual live slips, needing exceptional voiding, very rarely.