These are items we would have otherwise bought at the grocery or Wally World. And the prices are comparable for that purposes and I don't have to make a special trip to the store (usually for toilet paper).
The Dash buttons basically provide continuity of availability without hassle (going shopping). And it's more efficient than the "subscription" model since our usage of some products is variable over time (the day after Thai food sees a spike in TP usage in the house...).
If the prices are comparable, Amazon can have a couple of $$$, shoot, they even drop it off at my door, that's worth something to me. I'm very unlikely to comparison shop for toilet paper as I have a preference for a certain type.