Applying for US passports is much easier than applying for Irish/British passports.
If you want a US passport. you can just go to a post office (having made an appointment first), pay them some money, have them take your photo, swear you are entitled to a passport, show them a birth certificate or other suitable documentation, and wait a week or three for the passport to arrive.
To get an Irish passport, you have to get your photos and form signed by one of a tiny subset of the population who must have known you personally for at least two years. It's really tedious. Especially if you've only recently moved to the USA. British passports are less strict, but still a royal pain.
Also, you can't pay for an Irish passport with a personal check or credit card. Money order only.
Also, kids over seven have to sign their Irish passport application forms themselves. (I kid you not.)