You've probably had this drain snaked before. Maybe twice. It works for a while, then the slow drain comes back, and you start wondering why. This is what's actually happening. A snake does exactly one thing. It punches a hole through the clog so water can get through. But everything coating the walls of that pipe, years of grease, soap, sludge, and mineral scale from the county's hard water, is still in there, and the hole closes back up over time. That's not bad work, it's the wrong tool for the state your pipe is in.
Hydro jetting is the other tool. A high pressure stream of water scours the inside of the pipe wall, all the way around and all the way down, and carries the buildup out of the line. That's why a jetted drain can stay clear for a long time while a snaked drain often clogs again.
Is it always the answer? No, and nobody here will pretend it is. Sometimes a snake is genuinely all you need, and if that's your situation, that's what you'll hear. The contractor looks at what's actually going on, tells you what they see, and makes a recommendation. Then you decide.