Some of the features I really like about my Japanese toilet: * Heated seat * Bidet with warm water * “Omakase” power-saving setting that learns your schedule and turns off the heat during the times you are typically out or asleep. * Flush with a button press vs. turning a handle. This sounds minor, but whenever I have to use a toilet with a handle it is noticeably less convenient as you often have to keep the handle…
I have a strong dislike for typical toilet flush buttons as they are less sanitary and harder to clean. I feel if it's already electric then everything that can be touch free should be and everything else should be crevice free. A handle flush or chain flush also allows more control. I grew up doing slow flushes with minimal pressure at night for pee. It saved water and didn't disturb people.
Handles, on the other hand, also often have crevices and areas that are hard to reach for cleaning (on the underside of the handle or the area between the handle and the toilet). They also require more pressure, a larger contact area, and a longer contact duration, leading to more transfer of germs between the hand and the handle.
I agree that it makes sense for bathrooms to be as touchless as possible. My toilet will flush automatically when you stand up. Higher-end models will also raise and lower the lid automtically when you enter or leave the room.
It might be nice to have touch-free controls like you see on airplanes and some public restooms. But on the other hand there might be some design tradeoffs in terms of usability or battery life. And in a private residence, I don't think a flush button contributes significantly more to the spread of sickness than, say, door handles throughout the house.
In terms of water usage, Japanese toilets tend to be very efficient. The eco flush on my toilet uses 3.4L. The EPA's "WaterSense" certification, by comparison, applies to toilets that use 4.8L. So without more data, I'm a bit skeptical of the claim that it is possible to achieve better efficiency (and a complete flush) by using less pressure on the handle. To the contrary, I think it's probably more efficient to have the water enter the bowl with a higher velocity, as it would allow the water to get over the trap and flush with a lower total volume of water.
[1] https://toto.imagewave.pictures/GGA_14012506S154__web011.png...
