A button for garbage disposal before you have a chance to dry your hands? What does this button do, activate some pneumatic tube system so you don't have to carry trash to the bin?
It is an in-cabinet trash can with a mechanism to compress the trash when you push the button. I don’t know how common they really are. I’ve only know a few people with them. I could see where they might be more popular in apartments where you can’t easily take your trash to an outside trash can. They do require special, heavy-duty trash bags to handle the pressure.
I sympathize with that, more than once I've eyed mine's regular-light-switch and thought: "Surely the remaining water on my hands has too much surface-tension to go through any of those tiny gaps in the plastic... Right?"
I believe this is required by code in some places, depending on the location of the switch. Mine is inset into the counter top, so plenty of opportunity for water to pool around it which I think would rule out an electrical switch.
Mine is also in the countertop, makes sense that code would require it in that case. Previous owner didn't like the idea of wet hands on a wall switch.