Interesting! I read that it’s more effective to charge, say, 50p for a disposable cup than offer a discount of 50p for bringing your own cup. Psychologically, people rail against having to pay extra, whereas they’ll just shrug their shoulders at the possibly of a discount.
Tthe Vessel returnable cups scheme sounds an excellent idea. I think a problem with reusables when you’re out and about is what do you do with them once you’ve finished your drink? They’re a bit messy, so do you use some napkins to wipe them out? Or wash them in the loo and dry them under a hand drier? And you need a fair-sized bag to carry one.
Personally, I much prefer to sit down for coffee anyway, so really, it’s only an issue for me when we’re travelling and stopping at service stations.