key question for amazon:

how many doll houses is a person willing to return in order to make their soap purchase easier?

It'd only be a key question if one assumes the technology isn't going to radically improve over the next 5 or 10 years. It's going to. Deploying to consumers and dealing with such problems, learning from how millions of people use something, is a requirement of that process of improvement. It's similar to people questioning the GUI in the very early days of the PC, because working directly with text operating systems was still superior. It was extremely widely argued that GUIs were junk, were never going to catch on, were too slow, too glitchy, didn't add enough value etc - it's an obvious and common failure to look beyond the tip of one's own nose.

And what's the mark up on that compared to the grocery store? Considering shipping/prime subscription etc

There's Amazon Pantry, which has you adding items to a box, which is only sent when full. Thus the mark-up remains quite low.

I looked into it a while back. The conclusion I reached was that it might be worth it if driving to the grocery store/Walmart, shopping, and bringing your supplies home was a hassle for some reason. But Walmart tended to be cheaper than even Prime Pantry and you have to be somewhat selective in shopping in Amazon. (You'll find some items are randomly pricing.)

In my case, there's a Walmart I can drive to in about 5 minutes so stocking up on paper towels and dishwashing detergent every few months (and/or when I'm at the grocery store anyway) is pretty easy.

How often are you ordering dish soap that you need to streamline that process? Maybe it's because I live alone, but I buy dish soap maybe once a year.

Why not Dash if that is the entire reason?

Dash seems limited by being tied to one item. I don't get the appeal of Dash either because items I know I need a reoccurring supply of, I get a subscription to.

The Dash is a microsphone/scanner wand thingy, distinct from the Dash Buttons

I think the implication is "wet/soapy hands"

Think about what you're doing, and what condition your hands are in, the moment you use the last of the dish soap.