Certain pay at the pump stations won't work. And certain automated fare stations (although Ireland is fine). If you use an automated check out line at a food hall or such, an attendant will have to get a pen, you can sign the paper, and slip it in the coupon slot. I had only swipe cards in Ireland for 6 months back in 2016 and had next to no issues, except for the named. The biggest issue is drinking at pubs. If you don't purchase food, they typically won't let you start a tab. If you pay with a signature card each time, they will get very annoyed. As a rule of thumb, I just used cash unless I purchased some food.