This doesn't eliminate prep time, it just separates the prep and eating.

That depends on what you are cooking I think. Most things I am normally inclined to cook require me to attend to them while they are cooking. Slow-cookers eliminate that and do other things instead, like go to work.

Even if you are cooking something relatively hands off in your oven.. how often do you leave your home while your oven is on? You are locked down to that location for the duration of the cooking time.

A digital electric pressure cooker is a better option than a slow cooker in my experience. I use one. Pretty much everything cooks inside 20 minutes, even a whole frozen chicken. I cook tons of stuff straight from frozen.

But still, preparing the food once or twice a day is a distracting pain. It would be great if I could just stop off at street vendors or fast food stores and eat well, but as it is that stuff will kill you.

When cooking for one, a slowcooker will usually get me several meals. Still, healthy street food would be nice.

Yes it does eliminate prep time. You put a bunch of stuff into a slow cooker, add a can of soup like cream of mushroom for flavor, and it comes out amazing when you get home. Just don't end up eating too much meat this way. Use a lot of vegetables.

You don't have to stand over a stove watching stuff fry. You only have to clean one dish. You make enough for leftovers too.