I'm not sure that's a compelling reason. Why aren't frozen goods at the back of the store then?
And are you sure milk needs to be stocked from behind? Is it at the back of the store because it needs to be stocked from behind - or is it stocked from behind simply because its at the back of the store?
If you stock it from the front, then there could be a couple gallons in the back that never get bought. Unless they let the stock run out completely before restocking.
Plus with thing like milk, it is a real pain to push several gallons uphill to put something else in front (ever try to put a milk container back on the sloped shelf? Takes a couple hands and some fidgeting to do it).