i don't think that the removal of the border infrastructure you've mentioned, customs posts, diluted - reduced - division one iota. it did not lead to the island becoming a single unit in terms of planning, in terms of development, in terms of any form of policy setting. while the border posts might have gone in the early 90s, security checkpoints were still there until as a result of the gfa they were dismantled between 1998 and 2005. even so, the border is still there with taxation on one side very different from taxation on the other. donegal has not become tied in to its natural hinterland of derry or the other way round. the removal of the border infrastructure is basically cosmetic as on one side of it british law is enforced, and on the other irish. the essence of the conflict remains intact, namely that britain - despite claiming no selfish interest in the six counties - continues to hold it despite the clear iniquities of the division of ireland for the island's population both north and south.
the erasmus scheme is not taken up by many students from the six counties - 649 from the six counties in 2019/20. now the irish government will support ni students' use of erasmus (
Erasmus for Northern Irish Students from September - Fine Gael). but i don't know where they study, if protestants from east belfast go to study in cork or galway, and i doubt you do either. and it's a peculiar choice when over the period in which the erasmus scheme has existed divisions - inequalities - have increased in english society, in german society, in french society - it would be a great surprise if the erasmus scheme had had anything more than a tangential impact on divisions in the six counties.
none of this answers my query about what the cm/eec/eu did to dilute division in ireland in the 20 years prior to the creation of the single market, for which you've been utterly silent.
as for superiority, i don't feel personally superior to you. but the arguments you advance especially on this point under discussion - well, they're so feeble you'd do better not to make them. because from everything you've said brussels did nothing to dilute division in the six counties or the twenty-six except what they were doing elsewhere, that in other words they did not care.