Car Rental Insurance

Ireland is tougher with insurance. Car rentals there will make it very difficult for you if you are trying to not take the coverage they offer and use the coverage on your credit card. If you are attempting to do this, you will need to bring a printout of your specific coverage.
This may vary by company. My experience was with Hertz in Dublin.

This may vary by company.

This definitely varies by company and location. I have rented several times and have yet to need to purchase more insurance than is provided by my credit card company. 2019 I rented from Enterprise in Dublin (easy) and last year I rented from Sixt in Dublin (both at the airport). While they asked, at neither place did I get a hard sell. Also last year I rented just for a day in Galway from Budget in town. There were 2 agents and I got the guy NOT doing a hard sell, but the guy next to us was really pressuring a young couple. (I had read reviews and was prepared.) However it was not required.

Something may have changed since last year but the only required insurance was what was provided by my card. I did have documentation that Chase covers Ireland - not all cards do. Beyond that, it didn’t seem any different than anywhere else I have rented a car.

My husband and I are going to Ireland in June. We live in Canada. We called our credit card as we have a specific traveling card. They provided us good advice and sent us a letter to provide to the rental agency outlining what our insurance covers. We were told Ireland and Costa Rica have very strict rules.

We rented a car from Budget at the Dublin Airport in the summer of 2023 using our Costco Visa credit card, and didn't need coverage beyond that provided by the card.

When we rented in Ireland last year, I did opt for the CDW (Collision Damage Wavier) as my credit card let me know that they do not provide the typical type of coverage in Ireland. It added another maybe $250 to my rental, and provided effectively a zero deductible. This was worth it to me, and you need to decide for yourself it is worth it to you. Whether your credit card will cover a car rental in Ireland depends on the specific card and its coverage terms. Some credit cards, like those from Visa and Mastercard, may exclude coverage in Ireland (which my credit card does). It's crucial to check with your credit card issuer directly to confirm their coverage policy for rentals in Ireland.
Just like renting anywhere else, they will not make you or ask you to take on any additional optional coverage beyond what the minimal requirement is and what is already in your rental agreement, so you will have no issues there. I would just suggest that you indeed check that your credit card provides what you are hoping for it to provide should you opt out of the optional coverage offered.

I just got back from Ireland and Avis refused to honor my reservation because I had turned 76 and I needed a note from my doctor saying I was fit to drive. Avis had sent dozens of emails about the reservation and never mentioned that requirement. I was told it had to do with insurance coverage and most insurance and credit card coverage does not apply in Europe

and most insurance and credit card coverage does not apply in Europe

Hah! That is complete nonsense.

Call your credit card company to confirm that they do, indeed, cover the required car rental insurance in Ireland. None of our cards cover any car rentals in Ireland (which is common) but we are covered in most other parts of Europe. Because our cards do not cover Irish car rentals, I always tack on the rental agency's insurance. I've used Enterprise the last 3 visits and had great service.