Though T/b racing is horrible and makes the general quality of life for almost all T/b's awful (they're now bred for speed and their genetics make them frail and break down really early, they used to be great looking horses..) Standardbred racing isn't as bad. The horses last a lot longer and though they still don't always get the best treatment (as with anything) they have better chances of living longer higher quality lives.
In response to a previous comment, eventing is dangerous but show jumping and dressage can still be horrible. Dressage and jumpers have a tendency to develop ligament issues from not being conditioned properly. Dressage is extremely difficult on a horses' legs and can be harder on their legs than jumping. If a horse is trained properly the eventing isn't as dangerous as some make it out to be, though there is risk of course. The jumps being solid do add more risk, but again everything has risks.