I think in Australia we don't have the same problem because horses are valued a bit more.
A large percentage of horses in Australia live on the cattle and sheep properties, and are essential for mustering. A good working stockhorse is valued extremely highly, as can be seen by the high prices being paid for well bred, typey stock horses.
The horse culture in Australia is also very family oriented, often horses belong to an entire family of horsey people, and this ensures that knowledge of training and care and responsibility is passed down.
Also our horse community is quite closely knit and supportive on the whole, so if someone gets in over their head with a young horse then there is often help for them.
There are quite a few auctions in country towns and such here, and from my experience the most abundant breed present is the tb, especially those too slow or conformationally unfit to race. unfortunately these are also the prime candidates for the knackeries.
I think the difference here is there are quite a few genuine horse people that purchase at auction, and can recognise a horse with potential, therefore prices aren't as dirt cheap as you would expect.
mostly i think ti is just a difference in our dependance on horses, and as jazzy said the way we value them.