Milk is in the back because they have to maintain the cold chain, and the refrigeration is in the back. Putting it anywhere else risks spoilage if a pallet takes too long to unload or gets left unattended.

Try shopping in the UK.

None of the big 4 supermarkets near me have milk at the back. In fact IIRC they are all in the middle of the store.

Well, they're missing out on some opportunities to keep their products cold from production to purchase.