Oslo is a slightly curious one, as from what I remember you have to pass through passport control from a non schengen arrival before reaching transfer security (or any transfer admin), which then drops you into the schengen area, and you have to go back through immigration again to get back to the non schengen area (someone may correct me on that). So there may or may not be some potential documentation issues there, even before multi-sector onward travel by mutlipe nationalities on different airlines is factored in (plus BA's steadfast refusal to check anyone through on a different ticket, even without luggage)

But I seriously doubt airlines are willfully spending money on procedures or paper (or anything else) these days unless they have to. Not all passengers of global airlines are tech savvy and own whatever devices some of us may have. It can be easy to overlook that.

And the boardng pass wallets were no doubt an answer to a problem of people not being sure where to go and so highlghting the important details to reduce delays and offloads etc (a bit like the regular interrogations in AS recently). But those wallets are a very long time gone now. And just because one airline does something, or some passengers want a particular approach, doesn’t mean it is easily ubiquitous.