It's easier both to make trainers and use trainers on those platforms. For the 360, it would take a lot more effort to get the trainer working. For the PS3, it would take even more effort.
Because of that, there aren't as many people willing to use trainers on the 360 or PS3.
Let me be fair here... I am a customer of CH. I will happily pay for it. But I have no desire to pay $5 for a single trainer. This site makes me nervous. If CH finds that it's far more profitable to make trainers at $5 a pop, I see down the road CH going defunct - or stopping offering support and letting the existing memberships run out as they slowly switch over.
I know business is about profit, so I can't say it's what shouldn't happen -- but I don't have to be pleased. I will keep supporting CH because I like the current system.
Wow I like the new website guys its really cool. I don't mine supporting other trainer programmers out there. But cheat happens will always be my first stop for trainers.
I would love to make my own but I don't have the time or the know how