I'm sure it has something to do with being in a big city.
Not quite. They're owned by different branches of the same family.
http://www.slate.com/blogs/browbeat/2013/12/02/aldi_grocery_...
It is a knock on from the daily delivery movement to larger stores.
I think the problem Morrisons had was that they do all their own logistics, whereas the others use a mix of internal and external suppliers.
Citation? I still see Little Waitrose everywhere...
Morrisons do all their own logistics rather than outsource but their local stores did not fare well.
> The supermarket chain sold 140 shops for £25m. The stores made an operating loss of £36m last year.
They've out-competed a huge number of independent stores, since the supply chain of Tesco allows them to keep the small store well-stocked at relatively small cost, and with less floor space needed for a stock room. A lorry drops off two or three pallets of goods at the small store on its way to a supermarket. An independent shop can't compete with close to free delivery and the purchasing power of Tesco.
I used to live 5 minutes walk from a Tesco Express, and did almost all my food shopping there. I'd only go to the supermarket (15 minutes cycle away) if I'd run out of something unusual.
They also store less products in premium shelves and only the expensive brands (and no bulk for things like sodas, milk, etc.).