Thing is Dick and Jason had troubled lives they both were prodigies in their own right Dick being uber athletic, fast thinking and close to being the "pinnacle of human perfection" while Jason was pretty much a fountain of potential living in the harshest part of the city, by himself and actually thriving. For those two it was either become Robin and focus their talents for good or end up becoming super villains down the line. Batman knew this, you think it's possible for average people to learn multiple scientific/forensic/criminology subjects, language, tactics, fighting styles and other things all at the same time? Bruce did it because the only two things he had going for him was determination and money and he attained all of that over the course of 10-15 years, Jason and Dick will be 10x better at being Batman by the time they are his age. Tim is another story, he's pretty much lauded as being the best at everything his maturity and skills convinced him that Batman needed a Robin, Dick and Jason were drafted for their own good, Tim made a rational choice and volunteered.