Why is Dark Mode not the default for websites/apps?

[ehume]

Data does not go far without theory (and vice versa)

Data sometimes tells you your theory is wrong. That's why we test hypotheses.

[ashiekh]

And theory guides what data to collect

Take the example in this thread; had it not been hypothesized that a dark background saves a lot of power, data would not have been collected, and the data shows that it does not, but rather some small fixed power is used to power the LCD pixels. Together they have shown the initial hypothesis was wrong, but have also corrected it.

Without theory we would not even have computers, let alone computer monitors; same goes for data. Each alone is not very useful, but together they change the world; such is the so called Scientific Method.


As already pointed out OLED technology makes dark mode much more economical as each pixel is light producing.

Black does NOT turns off the pixel in LCD - they are just 'blocked' by crystals. But in OLED - they do, because each pixel can be individually turned on and off.
The backlight is always turned on in LCD monitors(I mean the most case without local dimming feature), and the voltage on-off per each pixel(liquid crystal) varies by its panel type.
If your LCD is TN or IPS, max voltage is applied when it's black. In contrast, VA panel consumes least when it's white.
But the power consumption from liquid crystal is relatively small when compared to backlight, so it does not make practical differences in RL.