Sales-people get paid to sell things – cars, televisions, real-estate, and everything in-between.
They’re incentivized to sell more than their coworkers. Bending a rule can give them an edge over their coworkers, but only until their coworkers begin bending that rule too and everyone is doing it. Then someone goes and bends that rule further, and the cycle continues until management actually enforces a limit.
You’re depending on the management of a corporation to protect your integrity and purchasing experience. Finding a good deal may not be easy.