However, they are almost all pastiche in style. The thatch is real - very real, very expensive and requiring very skilled trades to install and maintain it; but the pubs were not thatched originally, and some are or were new buildings.
As far as I can tell, the trend for this was started by the only thatched Dublin pub to have since been demolished (yet!), the S0440 Stillorgan Orchard, which was thatched in late 1988.
A number of other pubs were thatched over the next few years, as this trend proliferated. S0232 Glenside was thatched during a renovation in the 90s, with N0300 Lord Mayors in Swords being thatched during its extension renovation in 1992 (interestingly, lead by then the Douglas Wallace Opperman architects, the practice of the recently deceased Hugh Wallace). The Lord Mayors is to be demolished, removing another thatched pub from the county.
S0398 The Playwright in Blackrock - now a Dunnes Stores with a pub licence - was rebuilt completely in 1994, and thatched at the time. When converted to a Dunnes, the long unmaintained thatch was replaced with slates.
All of these four - and potentially more Dublin pubs - were thatched by Kyran O'Grady, a first generation thatcher - something I believe is quite rare, as it is more often passed down families - who is still working today.
N1128 Courtneys in Lucan is another pub which has a "modern" thatched roof, but I haven't been able to place when this went up, other than that it still had slates in 1970. This may be a 1980s/90s addition, or may be somewhat older.
On the slightly older scale, 1002618 Taylors Three Rock is reported as having had its thatched roof "added" in a review in October 1972, which indeed references there being extremely few other thatched pubs around - citing one in Galway as the only other.
I have severe suspicion about the integrity of S1583 An PoitÃn Stil in Rathcoole - this advertises itself in 1992 in a manner that makes me suspect it was first thatched then; and I cannot find a reference before them.
Now, not every Dublin thatched pub is a 20th century pastiche,.
S1580 The Rathcoole Inn's thatch, in comparison to basically everything else mentioned here, appears to be genuinely original - the trustworthy Heritage Houses of Ireland Facebook page speculates that it is "'possibly' Ireland's largest surviving historic thatched structure"
DG0478 The Man O War I think is possibly also genuine, has had some issues with its thatch recently - a fire which damaged it, but was not severe enough to force it to close for more than a day.