You make a valid point, sam_h, but I assume people are reflecting the language that is used on their workplace.
You are entitled to 20 vacation days per year. Your employer is entitled to insist that you take some of these during a closedown at Christmas, I assume that companies that do this, do not want to say " you get 16 days vacation + the Christmas closedown" as this sound worse than "You get 20 days vacation ( BTW, you have to take 4 of these at Christmas").
Niallers - the only people I have ever heard of in Ireland who get 30+ vacation days work in the public sector, or in universities, or in sem-istate companies.
If anyone knows of an exception to this, let us know.