I'm sorry, but I don't think I'll ever understand this.
If you go to Dublin, there is so much to see besides U2, it's such a great city. I would NEVER wait for so many hours, maybe even in the cold or rain, just to see the band for a couple of minutes or seconds.
When they are in the studio, the chances to see them are quite good, so there's no need waiting a whole day for them to arrive or come out. Information from various sources is also quite good and reliable nowadays. It's mostly stalker fans who are not satisfied with seeing them once or twice, but have to see and meet the guys every day and numerous times, as if they're collecting trophies. I really don't like this behaviour. They are ruining the chances of other people who only go there once and want to meet the band.
I don't think U2 are very happy with this kind of behaviour.
They are already giving so much to fans by being so accessible and open, but some people are just exploiting that. U2 could be asses instead as well and hide and run away from people instead of talking to them. After all, they're at work there, there is no need for them to meet fans every half an hour. They are really nice, down to earth guys.
People should just get a life and enjoy the sights and pubs of Dublin instead of hanging around a recording studio for days. That's just crazy.