And they ordered the POS software from two companies - at the same time. When the two companies finished the development, they paid both of them but choosed the better one which is now in production...
At least for the last incarnation in 2013 Aldi Süd took offers from 14 companies, chose 8 which delivered a proof of concept, then chose 3 to fully implement the software which was then field tested for three months.
They also have full rights to the source code and in-house developers to do small changes.
The hardware is supplied by a different company that also has software on offer. But apparently that is not good enough.
I've maintained for years you can tell how well a shop/chain is run by how fast it processes your card, McDonald's are currently the fastest I've found generally with Aldi running a close second.
Seems logical that once people have selected what they want to buy you get them out the shop as fast as possible.
They also have full rights to the source code and in-house developers to do small changes.
The hardware is supplied by a different company that also has software on offer. But apparently that is not good enough.