That&#x27;s one of the reasons stores offer sales, coupons, and similar: they allow stores to effectively offer different prices to different people, extracting more total revenue than if they had to charge everyone the same price.  A store could never get away with directly saying &quot;we charge more if you have more money&quot;.  But they <i>can</i> offer coupons and sales, which have the same effect: those who take the time to clip coupons and watch for sales pay a lower price (and thus buy anyway), while those who don&#x27;t pay a higher price.