Because you could easily contaminate the results of the urine if you don't follow exactly what the strict rules dictate This could be a very dangerous thing because if you contaminate the results, then other doctors would think that the patient has some disease that needs to be taken care of which in reality they do not. The patient could also have to go through things or waste money on things that they don't need to because there was something in the urine that wasn't supposed to be there which was added because they didn't follow the strict rules. Then the doctor who contaminated it could be sued for malpractice which is never a good thing.