How to encourage students to work more carefully and independently?
I recently heard a nice angle on this problem. Computer Scientist Olivier Danvy, adapting Buddhist philosophy, stated in a recent presentation that you need to inhale before you can exhale. What he meant was that in order for grad students to produce quality work, they need to see, read, ingest and understand quality work. Perhaps you can show them the difference between the high quality work and low quality papers you've also come across. Try to get the student to gauge where his/her work fits in relation to these other papers.

You'll also need to explain that even though poor quality work can actually be published, that this is not a good thing. Not good for science. And not good for building a career.

Many iterations of corrections is important. It takes time. But for every comment that is ignored, you need to find out why it is ignored, and make the student aware that it takes your time and is annoying if you need to make the same comment over and over again. Maybe the student does not understand the comment. Maybe the student is overwhelmed by the vast amount of comments. Maybe that just missed it accidentally. Maybe they just disagree.