What I have also seen in the Hypercarrefour in Bruges that they scan your groceries when waiting in line to the checkout. Then they print a ticket on their mobile printer which you just need to give to the checkout and pay.
A local Delhaize (Food Lion in the US) experimented with a fixed POS where you needed to take out all your groceries, self-scan and pay. I have also used the same system at Tesco in Prague. Not the most pleasant system in comparison than the mobile version Carrefour and also Auchan uses where you just walk through the store with a mobile scanner.
Other local retailers (colruyt, aldi, lidl, Albert Hein) are more classic in that regards.
"t's often broken, and some items are subject to different buying conditions and can't be purchased via these self-service checkout lanes, like alcohol, or "luxury" items with high margins, like razor blades."
To be honest that's not a problem when using self-scan at Carrefour. Only if you buy alcohol or tabaco they may ask for your age or if you are picked out for an inspection. There is no limit in what you buy.
Although that is the situation here in Belgium.