Rooting your phone is not a DMCA violation. sudo simply is not pre-installed, it's an app you have to add yourself, just like anything else. Reverse engineering for interoperability is a DMCA exception, and there are plans to make the language in the law specifically refer to "jailbreaking" phones.

Also, at least with Android devices I've worked with, there is no trickery involved to flash a new firmware. You just do it.