For some time now, there has been a great larger display at the cash registers where you can see what the cashier is scanning. You can also see promotions very clearly from the orange color etc. etc.
But what is (still) missing in my opinion,
At the end, e.g. with the total amount, the customer should be able to see the following:
1. Cumulus was recorded (e.g. picture with Cumulus card)
2. which activated vouchers or vouchers scanned by staff have been recorded.
(Especially in the case of self-activated vouchers via the app (e.g. 2-fold, multiple, etc.), otherwise you sometimes have to ask whether it really took them. Technology sends its regards?
Some cashiers point this out themselves, others don't and I personally think that the staff already have enough work and do a great job anyway, e.g. when asking if you still have vouchers to redeem or something).
I think these points are certainly technically possible.
With self-checkout and self-scanning, you can also see the activated or scanned paper vouchers.