My point, probably poorly expressed, was that it's not realistic to expect the school to instill that sense of responsibility in the child, and that the "check and sign this" policy is really just a gentle encouragement to parents to take an active role in their education.
I guess what I was getting at with the irritated part is that without my signature on the homework, it's deemed 'incorrect/incomplete'. This is teaching my children that they must rely on me for their own success. It's not that the school is not teaching responsibility (agreed that's my job), but that it's teaching dependence.
I also suspect that in many cases the work itself isn't looked at, a signature from me is looked for and that's it. If that's the case, it's a situation where the school is giving homework for the sake of giving homework, which I don't think is correct.
Err, isn't it the parents' responsibility to build responsibility in their children rather than the schools'?