My brother is a nurse - it is a tough job. Look at it from their prespective. They are very busy, they literally have a person's life in their hands as in if they make a little mistake it can be life threatening....think you just read the medication instructions wrong and give a little more than perscribed and many other things.
They probably do not have a choice on training/working with you - but they still need to do their full time job while ensuring perfect care with no mistakes - and most likely they are already overworked so then they throw you onto it and they need to train you on top of their already overburdened and stressful job.
No it is not your fault, but really if you make a little mistake - it could cost them their job, and maybe someone's life.
If you tough it out though - it can be rewarding. It isn't an easy job, but my brother has been at it for 20+ years. One thing when you are ready - it is best to work in a high quality hospital.
He worked as a traveling nurse and one time at a lower quality hospital...he called a doctor during the doctor's off hours because the medical instructions were not clear and he of course had the patience best interest in mind and wanted to verify. The doctor yelled at him for disturbing him in off hours. So you can see why nurses can act that way.