Yeah, it's pretty weird. Test and basic glasses are free or near-free for most people in Ireland (if you've got a job it's covered under PRSI, if you don't it'll be covered by the medical card). If you're covered by neither (ie fully private), ~60 euro. I'm not sure what's stopping US vendors from just importing glasses from Europe...
Because people can go long periods of time between exams/pairs as adults, it's possible they keep their cash prices low to convince the uninsured to step in the door.
Private optical insurance _exists_, but basically only as a corporate perk that pays for more expensive frames, etc. Most people wouldn't have it, and it didn't exist at all until a few years ago. Private health insurance is more common, but doesn't pay for glasses or routine eye tests.
I believe PRSI (the government social insurance scheme) pays about 30 euro for a basic eye test. At the big local chain, people without either PRSI or medical card (this would mostly be non-resident foreigners, plus maybe some early retirees etc), pay 30 euro, plus about 60 euro for basic frames with basic lenses.
