This is a common practice in many places around the world. The most often-cited is sushi in Japanese supermarkets being discounted throughout the day. But there are also a couple by-the-pound buffets in the city that discount after 2pm, as well as my local Chinese bakery in Queens which sells everything 2 for $1 after 7pm.
Here in the US, however, the general corporate philosophy seems to be that they'd rather waste food than "devalue" their merchandise by selling it at a lower price.
So when I do notice a place that adopts an intraday discount policy, I take note. Do we have a megathread for this? Or perhaps we can start one here?
I'll start with one I found recently. Olympic Pita (now in a much smaller storefront on 46th street after it closed its 38th street location) everything on the menu is 50% off after 2pm on Friday. They keep kosher and don't open on the weekend, so this helps them not waste food. Their laffa (home bread) is still pretty good in general.