Andúil 2, a popular user interface for flashlights, operated by one button

Because it's "elegant" and you're gonna sit there and TAKE IT.

I also wondered this (while I admire the design here) and I think this has all to do with speed. These flashlights are used in security, hiking, rescue, where you can't be bothered with fumbling with buttons, also xour other hand is probably occupied. The patterns are lean and can be learned when done often (thats the whole point of this design), and after some config, things can be accessed with a few taps.

That's mostly a hardware matter, of how to make a multi-button flashlight. Handling more buttons in the firmware is no big deal. I have one of these lights and have hacked on the code a little and it is pretty understandable. It is written in C and runs on ATTiny processors, and you compile it with avr-gcc.

Pro tip: most flashlights that use it don't have a good way to actually reflash the firmware. Try intl-outdoors.com for some very nice ones that do. They sell an accessory reflash kit and you'll want that too.

Dang, can you fix the title to correctly spell "Anduril"? That will make it easier to find by search.

There is no click-wait-click in the default Anduril UI. There is too much stuff to memorize, but most of the complexity is for configuring the flashlight the way you like it (indicator colors, UI options, etc.). I.e. you buy the light, sit there with the manual setting it up, then leave it that way. Then it's just click on, click off, hold the button down to make it brighter, click-and-hold to make it dimmer, or double click to temporarily access the brightest level. The other stuff is not worth trying to remember.