I have. Lots of them, all over the world. On every ship I've worked on the track pilot is used for hands off operation. Hell, some guys would do paperwork or work on stowage plans during their watch.
> No, just the common understanding of autopilot for aircraft.
The autopilot for a aircraft does whatever it is supposed to do without human supervision. If you turn on keep heading, it will keep the heading (within physical limitations). I guess it is similar for a boat.
Lane assist, however, requires constant human supervision because it is just an assistant. I think this is the important difference that needs to be highlighted here.
I see you've never skippered a boat.