That's not necessarily true. The LS computer is not magically open and free like everyone seems to think. They are encrypted just like Mopar stuff, the difference is mostly volume. There is enough demand out there for LS tuning/modification that aftermarket companies put a lot of time and money into cracking the encryption and decoding how the computer works. The Mopar stuff doesn't work any differently in a certain sense. It still takes inputs from sensors, does math, and controls outputs. The difference is that the aftermarket doesn't see the return on investment with dealing with them for whatever reason. There are some companies (Diablosport for instance), and HP Tuners has started to get some support, but it's not nearly as deep.
I just get tired of everyone thinking that LS computers aren't encrypted or that the factory hands over the keys to the aftermarket. That's simply not how it works. All systems have security. Maybe some are worse than others, maybe even intentionally, but I find that awfully hard to believe. As a company, I wouldn't want to hand over the keys to my expensive product to some backyard mechanics who think they know more about tuning than people who do it for a living.