Bad Samaritan, I see where you're coming from. Poland is probably the most religious country in Europe hence the lack of Polish porn starlets in comparison to other Eastern European countries.
As for Ireland, it's still pretty religious especially in comparison to the UK. Moreover, there are other considerations as to why it would never be a great place to film porn.
1) The wage disparity between doing porn and another job in Ireland isn't nearly as great as it is in some other countries;
2) A small native population - nearly 7X less than England and 10X less than the UK;
3) Only 1 large city (Dublin) and the rest (Cork etc) are really towns. Compare this to the UK: London, Birmingham, Manchester, Leeds and Liverpool are all larger or of equivalent size. You've also got lots of other smaller cities nearby - Preston is near Manchester/Liverpool etc. All these cities have lots of lapdancing bars etc. There's simply much more in the way of talent.