Many of those listed are considered careers destinations.
My current job has a training contract! Considering that VERY few seem to leave this job I was very surprised at this fact, but it seems that many moons ago that the job was yet another stepping stone to the airlines and there were people who got the job, got the one or two type ratings, and then bolted for the airlines.
Businesses that operate on the most razor thin of profits obviously have the most to lose from unrealized gains from investments.
Look at this way. When YOU invest money, you want to see a return on it. You would not be happy if the investment banker took your money and ran off to the hills

There are bad parts of a training contract. I don't like the way they are one-sided for instance. I don't know what the answer might be - especially for an industry as volatile as the airline industry. Another poster mentioned being stuck in one job while another comes available. I was very nearly in that exact situation when my present job offer came open. The company I worked for did not have a formal training contract, and unfortunately I had just completed training on another type of aircraft when my initial type was grounded, but I gave the company my best efforts, as much head's up as I could, and explained that I couldn't pass up a real career move. I even delayed starting my new job until the latest possible start date. If my out brief was as honest as I hope it was, my former employer and I parted ways on good terms.

In the end, I hope that the new contract doesn't have a training clause embedded either, but I do have a hard time seeing any and all training contracts as the evil that they are often portrayed as on this forum; but then again I've not worked in an industry that has quite the poor labor/management relations as the general airline population either. I guess I don't automatically assume the worse in all measures.