Originally Posted by
RobOnLI
Non-EU/EEA/CH passport holder here. Recently flew to Dublin and went through passport control. When they asked where I was going I mentioned Belfast. The RoI immigration officer asked if I had an ETA for the UK. I did as I've "used" it many times already. But it's not the RoI's job to care about the ETA which I found odd.
-RM
Its really not that odd if you think it through.
Immigration is simply making sure you have the means and intention to leave the country to which he/she is granting you temporary access. This is the more likely if you are not leaving on a return ticket. Had you said you were going to Cork, he/she would have asked you how long you were intending to stay in the country. Saying you're off to Belfast suggests you don't have that return ticket to a jurisdiction where you are entitled to reside long term or permanently.
What immigration don't want is you being returned back from another jurisdiction, or prevented entry to that other jurisdiction, it then becoming a big head ache for all.