The comparison with Switzerland is not really accurate to be honest. You'd want to be comparing with rural Northwestern France, parts of Norway or Scotland to get anything remotely similar to the West of Ireland in terms of population densities and spread.
Then you have to factor into the mix in Ireland that there is no onward connection to major urban centers and absolutely no way of using long-distance rail freight.
If you take a look at a country like Spain for example, which has excellent rail infrastructure, far flung and low population centre cities like Pamplona are only served from Madrid 4 times per day!
Pamplona has an urban population of 198,000 and a metropolitan population of 319,208, so it's about the size of Cork.
Dublin-Cork can justify more services because the distances are shorter, but even so similar population centers elsewhere do not really get stellar service.