I've had 3 experiences at 3 different colleges, and 2 of the 3 didn't count attendance at all. It was the student's responsibility to find out what was missed and complete it on time, but no one was taking attendance and penalizing students for not having their butt in the seat.
This was the case when I was a college student too, but I understand this is changing. Do you know what a Senso is? It's essentially a remote control, which students in a large classroom setting use to interact with the professor during lectures. (Stick with me, I'm going somewhere here.)
The teacher can put multiple choice questions on the board, and the students "click in" their responses, giving the teacher an instant feel for how well the students are understanding the material. It's a way of keeping students engaged during a lecture. Kids LOVE them.
College professors are requiring students to buy these gadgets for their classes, and they're using them to take roll in large lecture classes. I heard that one university in our area is toying with requiring students to have an iPhone because it can be used to do similar things.
The bottom line is that college is changing rapidly because of technology, and attendance IS being measured to a greater extent than it was in the past.
I think the reasons American kids are often ill-prepared for college is that so many schools fail to challenge college-bound kids that the brightest kids don't develop any study or work habits to speak of. When they start college and find themselves having to study, it is an entirely new experience to which they have trouble adequately adjusting.
I think this is happening for multiple reasons:
Money has been easy to borrow in recent years, and people who otherwise might not've gone to college have decided to give it a shot -- whether they really belonged there or not.
Too many students don't spend enough time reading; instead, they're relying upon quick and easy technology -- and while that might get you by in high school, much of it looks like a flash in the pan in college. Too many of our students use technology only in a superficial way; they know how to "google" and they know how to use software, but their underlying knowledge is lacking . . . PLUS they don't have the good, old-fashioned skills that comes from lots of reading, figuring math with a pencil, etc.
We as Americans have developed the incorrect idea that "everyone" should go to college -- again, whether they belong there or not.
And, of course, there's a great deal of merit to your argument that the best and the brightest aren't being challenged enough. Somewhere along the way we've decided that no one should fail, and that's dumbed down a great deal of material.