Bias built into the law.
You would think that it would be the teamsters who should be required to ring the bell, not the pedestrians. Another example of the law always favoring the big shot, and putting a burden on the little man.
I guess if you can't afford a carriage, or if you're not a merchant with a fleet of wagons, its up to you to look after your own safety. After all, you wouldn't want to get run over and delay a delivery.