Why don’t more people commute from Northern Ireland?

I don’t mean to offend or sound insensitive, just had a question in the back of my mind: A lot of people on my previous post suggested I live in the North and work in Dublin. I’ve been doing my own research and rents in Newry vs Dublin are at opposite ends. I wanted to ask in case I’m missing something here: why don’t more people live in Northern Ireland where things are cheaper and just commute. There is a direct train from Belfast and Newry just seems and hour away from Dublin.

Once again, I don’t mean to sound offensive or sarcastic or anything. Just asking.