As someone who has been involved in the racing industry I would say that racing in the USA leaves a lot to be desired.
For a start the going on a lot of the tracks leaves a lot to be desired. Racing on dirt can mean racing on sludge or hard going or, worse still very uneven going.
Secondly, horses in the US can and do race when on drugs because as long as it is declared. A horse that needs bute to run is not sound therefore should not be running. Lasix for a bleeder also means the horse is not 'right' so should not be stressed.
If a horse is given pain killers to hide a lameness or even the fact that a horse is just sore, and it races then whatever is causing that problem is under a lot more stress and the horse, with the effort of racing, will have more major problems.
In the UK there are nowhere near the deaths on the track flat racing. A lot of this is due to the fact that the horses are raced a lot less, they generally run on grass and are trained very differently. There are going to be fatalities and injuries but they are far less this side of the pond than that.
I would like to see two major things, the first that America falls into line with the banning of all drugs when a horse is racing (means withdrawal several days/weeks before a race) and limit the number of races a horse under the age of four can run in during a season.
Surfaces should also be looked into, there are far better ones than dirt.