Why do university take PhD students on there ability to pay not there ability to do the work?

[studentsahhhh]

Sorry need to have a rant.

I have a PhD student who is awful, she's doing a very science, hands on PhD which requires her to calculate concentration and dilute solutions. She just has to read the pre-set protocols but can she do this no!! I ask her to do something simple and explain it to her, she comes back 3 days later and has't done it so i explain again low and behold 3 days later still not done! because she can't do it. i have held her hand in the lab and gone through stuff with her in great detail, when she writes it up it is quite plain she hasn't understood. all i want to know is why is she here! she can't do the science!

ahhhhhhhhhhhhhh

sympathies - I cosupervised one once who was never in a million years of PhD standard - he passed - bloomin thesisi was unreadable and full of c* experiments - mockery city when the £££ and failure stats count