Yes, it is a landing card in advance, but if you are refused, they say you should either give up your trip or apply for a visa. But as visas take longer, you end up having to give up your trip, at least for this time around.
And you are right, they did say clearly that getting this authorization is no guarantee of entry in the country, and also, by filling in that form you give up all sort of rights and more or less they can use that information you provide as they want, keep it forever, pass it around etc...
I meant that in the email they received there was not written what information they would have had to provide, and they didn't bother to go and see the instructions, as it said 72 hours in advance, they thought they were fine to go back to it later on. It's only when I was told she didn't yet had her passport (I didn't know she didn't) that I told them that was necessary in order to fill in this form and caused panic because it would not be ready in time. That was not a comment on a bad service from the airline, just a rant on how annoying this thing is... It was all a last minute thing, their decision to come to the wedding, they decided to come only 2 weeks ago, for a departure date of next week, and it has increased my stress level exponentially...
Actually, I am wondering, how about people who have to just jump on a plane and go, I am thinking in case of sudden illness or death of family members, or for work etc., what would they do, will they HAVE to postpone their flight 72 hours later, if it is the first time they fly under this new system? Especially in this first phase, when the necessity of this authorization is new. I can imagine that they can always say they had an interim period in which it was not compulsory... Sigh... I just wish things were simpler, it's an added thing to take care of when I already have so much to think about, with the wedding and all...