" In the real world you dont get several try to make a pitch to business, or build a bridge, or operate on a patient. "
Mostly, you do. Don't be so dramatic. Structural calculations on bridges are checked and rechecked. Pitches are produced, and often presented, by teams. The recent studies on checklists for surgery, taken from aviation practice, are precisely to get multiple eyes on the same tasks. The whole field of CRM (Crew Resource Management), post Tenerife and Kegworth (in particular) is an exercise in trying to avoid the myth of the lone pilot whose skill is the sole salvation, and it's noticeable that Quantas (famed for having a shallow power gradient in the cockpit) has never had a huil loss, while Korean airlines (which have massive problems with CRM) lose hulls with monotonous regularity, most recently the San Francisco accident, which appears to be pure CRM.
"Performing under pressure" matters in a tiny handful of occupations, and is selected for in the later stages of getting those jobs. And even then, most of the training is about removing the pressure, not about performing while it's there (to return to CRM, the "aviate, navigate, communicate" training is about giving people time and space to think clearly, not about making pressure decisions while everything goes mad; surgeons are trained to make the best use of the people around them, rather than being the lone hero of yore). There is, yes, a time and a place for some people, for a small number of jobs, to prove they can make snap decisions well under pressure, most of them military or emergency services. That time, and that place, is not GCSE English being sat by a fifteen year old (I have a summer child).
" If you want to train a professional driver, would you pick someone who took seven attempts to pass or someone who passed first time? "
I don't know: you tell me. I think you're falling into the "good stick and rudder man" or "natural driver" myth of driving and flying, that it's about some sort of "talent" which trumps process and experience. Endless confidence is not necessarily a good thing. Yet again, remember that the worst aviation accident in history, Tenerife, was caused by the Chief Training Pilot of KLM, a man who had passed all his exams with ease. Perhaps had he had a bit more humility, 583 people wouldn't have died. Michael Schumacher was never the fastest driver, nor the most natural (source: a race engineer who worked with him and others), but he won quite a lot of races by being the best prepared, the best trained, the hardest working.