Two points re: Irish "crest" tartans:
(1) they aren't crests, they are the coats of arms of the various counties and as such are the copyright property of the Irish government, the copyright being vested in each local (county) authority. Not that the government does anything to enforce that copyright.
(2) not all of the arms are correct; certainly the arms of Dublin are not those depicted.
(3) while the city of Cork has arms, the county does not.