I have very mixed feelings about flat racing as the horses are raced before they are mature but I've been to several racing stables and know lots of people in the industry, IME the horses are very well looked after and many will be retrained after their career ends. I've owned an ex racehorse, he'd gone on to be quite successful as an eventer and came to me in his early teens as a hack and dressage horse. He was a lovely sensible horse and my 14 year old daughter used to do some PC stuff on him.
However, no horse should be transported when lame or sick and having watched last night's programme I was appalled to see how horses were being handled and euthanased . What I saw was illegal as well as cruel and I fear there are some very unscrupulous people out there but they do not, IMO, represent most people involved in racing. I don't have a problem with horses being PTS, often it's the kindest thing to do but it must be done well and according to the law. fwiw, the whips used in racing are highly regulated and make a noise rather than inflict pain. Every horse I have owned has had a mind of it's own, horses won't race or jump if they don't want to, I had a little TB who had never raced but he loved to gallop, always wanted to be at the front and lived a full and happy life until he was 28!