Can't tell you how many guys have shown up for instruction at the fields I have belonged to with the ailerons reversed. I would guess as high as 10% of first timers. If they were on their own the first flight would have been short and unpleasant.

An instructor can "check you out" and in 20 minutes relate enough tips and suggestions that you couldn't pick up in 50 flights on your own (If you made that many) as well as balance and trim the model so you have good chances of success. Simulators just don't have the impatience, bravado (with an audience), nerves, cranky engine, low battery, warped wing settings, high grass, bumpy runway, flukey winds and overly lean/rich engine problems worked out to simulate a real trip to the field.