It is even more absurd when one considers that `the UK is presently a Member State and thus EU has been used in this context to refer to all Member States other than the UK.
The value of these tickets comes from the EU requirement that a service, e.g. an e-ticket offered at a given price anywhere in the EU must be made available throughout the EU. Not so elsewhere.
Thus, a UK resident who finds a better fare originating DUB may purchase that DUB origination at the price offered in Ireland. Throughout the rest of the world, carriers which wish to engage in market-driven price discrimination simply limit the residency of the purchaser.
Whether that will be required post-Brexit and whether carriers would offer it even if not required, is something no person, including the negotiating principals could remotely answer today. I trust that there are a few other issues of more significance.