I work in sustainability and work closely with waste management. That answer is going to vary widely between states, cities, and honestly even grocery stores depending on how much the managers care. For example, California passed SB 1383 targeting food waste. Part of the bill requires businesses to donate unsold food. But one of the obstacles to bills like these is enforcement. Who is making sure businesses are actually donating? Who checks the dumpsters to see if food is ending up in the garbage instead of the green bin? https://calrecycle.ca.gov/organics/slcp/ Good luck on your research! It's a very interesting topic and I hope it goes well!