As far as vouchers go, companies probably want some friction to keep profits up where people forget to use them, but also get people in store to spend more. Automatically applying vouchers probably isn’t in their interest.
They want to be appear to be benefitting the customer without sacrificing revenue.
Tesco and Sainsbury’s now don’t print receipts by default, you have to select you want one at self service, or say yes when the cashier asks if you want one.
For a nationwide receipt service, companies would be more likely to go for it if they had access to your other receipt data / where you shop so they can market more crap in your direction. The data that Tesco collects for club cards is a lot more valuable to them than just handing out points, they can probably create quite in depth profiles based on club card info, if you signed up for stuff like ‘baby club’ and the frequency you shop. I imagine the data helps quite a lot to contribute to store layout and staffing requirements.