Just posted a comment regarding the data, which comes from the UNEP Food Waste Index Report, we simply visualised it in a map.

With regards to infrastructure, the report does mention that the authors encountered a lot more hostility and resistance when attempting to conduct waste audits of food service and retail companies. Considering that food waste is a commercially sensitive topic (and these companies looooove money) it makes sense that they don't want to give accurate numbers. Your suggestion is plausible but we probably won't know for sure unless these food service companies give us accurate numbers.

Plus, the report also suggests that there is such a wide scope for the definition of "food service establishments" - imagine the difference in wastage between sports stadia (beers being thrown after a goal is scored) and a hot dog stand down the road!