2 yesr old horses are best for racing

Everyone knows that the big money in racing thoroughbred races are run by 2 years old. There are a lot of controversy about whether they are ready and certainly some of the recent events in the past might suggest that it is not. Thoroughbreds usually grow faster than Warmblood, and I do not know about Arabs, Quarter horses, or other races. I know that it is important that the growth plate is closed and the horse is physically ready to do the job are required or may be injured at some time in training. The mental maturity should also be considered but I do not think some people will agree with me.
We do not do something different with our 2 year old in the first 6-8 months than we did when they were tormenting. They live mostly outside, with occasional trips to the barn to the vet or farrier grooming. They can also go to a show breed, so we will work with them by the hand, and they're bound to get a shower, get their faces trimmed core pulled and loaded into a trailer. Otherwise they are left alone to continue growing and just being a horse.
The last part of their 2 year old year we will start training them on staff line and voice commands. We also do some free lung and free jumping, mainly to evaluate their gaits and jumping ability. This happens in short 15-20 minute sessions 2-3 times a week. When we see how they react to this practice and how willing they are to do what we ask, we can decide how long to continue. Some of our young Warmblood respond in a quick and easy, we only worked on it for a few sessions, and then left them alone until spring of their third years. We want to see that they are comfortable in practice and that they understand and respond well. It was great when they're curious about what is happening and like attention practice - the horses seem to want to do what you ask, waiting for the next new lesson. That is what we are trying to achieve every young horse, some will not need a lot of repetition to get there, while others require frequent, short sessions. A lot of patience is sometimes required by the coach, but we really try to make training fun and not serious in young horses. It really pays off later when we start asking for more and there is a relationship of trust established.