I'm sorry but you're missing a huge point, I used to work for Apple and many people don't realize the lack of warranty involved with jailbreaking a device. Jailbreaking the device leaves you without any warranty on the device as it's using the system in a way that it wasn't originally intended, same with Android if you root that device there are counters embedded in the system (yes you can reset them with the right tools) but the point being that there are ways of telling that it's been modified and run outside of the agreed software state, therefore out of the warranty.
I'm saying this because I used to hate it when people come in with iPhones they've bought from a mate that are unlocked as far as they are aware but in actual fact the previous owner used cydia to hack the modem firmware, the customer hasn't realised it, done an official Apple iOS update from iOS 4 to iOS 6.1 as an example, and their modem isn't recognizable and therefore the mobile won't activate no matter what and is a brick. Which brings it back to the point of it's out of warranty because the official Apple software wouldn't have done this. Leaving this innocent customer the one wounded.