Dublin has pre-clearing[1] arrangements for entering the US so you can do all your checks in IE. Most of the US companies registered in Europe are in the RoI/UK, which could be reason for why they exclude it. Also whether this makes sense for "containing" is a different question.
If you have ever traveled to US via Dublin before you will never want to travel from another airport after.
[1] > Dublin Airport is one of only a handful of airports outside North America that offers a US Preclearance facility. The benefit is that having cleared USCBP, passengers arriving in the US are treated as domestic arrivals, allowing them to avoid immigration queues upon arrival and pick up their bags and go.https://www.dublinairport.com/flight-information/travelling-...
If you have ever traveled to US via Dublin before you will never want to travel from another airport after.
[1] > Dublin Airport is one of only a handful of airports outside North America that offers a US Preclearance facility. The benefit is that having cleared USCBP, passengers arriving in the US are treated as domestic arrivals, allowing them to avoid immigration queues upon arrival and pick up their bags and go. https://www.dublinairport.com/flight-information/travelling-...