A word on the US system. The question bank is published along with several crammers which will virtually guarantee a written pass.
BUT...the ppl Candidate is orally quizzed by his Examiner for up to 4 hours before his checkride. If he fails the oral he doesnt even get to fly, its a fail and "come back next week", along with a word in the shell like appendage of the CFI responsible.
The Ground Instruction in the US by CFI's is charged at the same rate as flight instruction i.e. 1 hour flight plus 1 hour's brief=2 hours pay for the Instructor.
So USA = cheap aeroplanes and expensive instruction...UK= expensive aeroplanes and instructors on the breadline.