If a kitchen line in Carlton Hills or a bathroom drain out by Santee Lakes keeps clogging a few months after every snaking, this is why. The cable opens a path, but the grease, soap and scale coating the pipe wall stay put, and the same spot closes up again.
Hydro jetting sends water through the line at high pressure and scrubs the pipe wall the whole way around. Instead of a path through the middle, the buildup gets washed out of the line.
Not every drain needs it. Sometimes a simple clog just needs a cable, and if that's the case, that's what you'll hear. The contractor looks at your line, walks you through the findings, and you decide.