Ellie, memories came back to me as I was in bed last night. My Killarney visit was a brief stop, en-route from Cork to Tralee. Stayed in a farmhouse near Killarney. I was taken aback at the commercialisation of Killarney. It was unlike any other Irish town I'd known. As Elwyn said, Killarney was an earlier adopter of tourism. Tippling down most of the time I was there (August) so jaunting cars were getting little custom. Take a waterproof coat & boots or stout shoes.
Then it was on to Tralee for the Fleadh (national traditional music festival), which I was reminded of in connection with a recent RootsChat topic about a musician who died in Tralee.
Extensive railway development in Ireland happened about a decade later than in Britain. The first line, 1834 was a short one from the mailboat port to Dublin. More lines were constructed to link up towns and cities in the 2nd half of the 19th century. Extra trains known as "Harvest Specials" were put on each year to transport thousands of workers to & from east coast ports so that they could travel to farms in Britain. My GF in rural Mayo lived 8 miles from a station (opened 1861) on a mainline to Dublin. He and his relatives would have travelled on the "Harvest Specials" when they went to work on farms in England. When at home, he drove a cart to the station to collect supplies for a relative's shop.
A pre-railway form of travel in Ireland was the Bianconi coach (1815-1850s).
Another thought about dress. I think few women in 1920s Ireland would have owned a pair of trousers. Divided skirts were worn by some schoolgirls and some women for sports. Pupils at my secondary school wore them for games until 1950s.
I think the one at the end was the only woman who'd dressed that morning with the intention of going horse-riding.