[Mithorium]

lazy actor: I print out the barcodes, and stick them on the paper rolls at random

bad actor: I manufacture the cheaper rolls, and stick labels for the expensive ones on, and scan them

How will "the blockchain" prevent either scenario

[Drdrdrq]

Lazy actor: receiver will scan the codes and see that data doesn't match, thus they can't trust the sender.

Bad actor: unless you intend to use rolls by yourself, what do you gain? You can't sell the better rolls as such, because you have broken chain of trust.

But such arguments lead nowhere. Of course you can come up with scenarios which can be misused. The real challenge (and one that is being solved by lots of people in crypto world - well, at least those that aren't consumed by greed) is finding scenarios that work. The ability to store information cheaply and immutably can change many industries, but technology must be deployed in such way that it makes sense.