This is loose reasoning - it is true that photons are the same, but completely over simplifies the problem

Some addition things worth considering

Effective intensity of observed object (last I checked, paper isn't a mirror and doesn't reflect very well)

Frequency profile of the light being observed (cf light from the sun being imperfectly reflected vs lamp being reflected vs direct light source)

Ambient light around observed object which affects both stimulation profile of receptor region of eye AND pupil dilation

So yeah original emitter source isn't the only piece of this puzzle

You see light that comes from a lamp and is partly reflected, partly absorbed, and a bit scattered along the way to your retina. With screens, you're looking at the lamp.

Doesn't matter where you're looking at, only the intensity matters (and you can control that).

Whether you're looking "at the lamp" or at a newspaper that reflects light, the end result is the same: photons hit your eyes.

you can stare at the sun to be more productive when viewing the sun as well. /s

No, I don't buy the green screen argument, any more than the randomness of paper being somewhat white and ink being in contrast to that. Certainly white on black is useful in astronomy, the stuff you are interested in is lit. This article was such a wall of text, I don't know if it ever supported its conclusion very well, which is ironic for an article promoting "productivity".

>you can stare at the sun to be more productive when viewing the sun as well. /s

Not sure what this even means, sarcasm or not.

If the sun could be set in "low brightness", like a screen can (and ignoring infrared), then yes, you _could_ stare in the sun.

The light is very different in intensity and colour, though. Reading on a phone is more like reading a newspaper that's being held directly under a very bright light.

Every time I try to use a screen outside on a sunny day, the "intensity and colour" of the outside world seems to massively overpower it.

Agreed. I spend a lot of time working outdoors. Even in the shade in the summertime, I have a shell profile with larger fonts and a dark-on-light color scheme to make it easier.

Simply turn down the brightness. The intensity can't be the issue because you can adjust it. The colour could be though - even at the same perceived colour temperature, the white light of the screen is going to have a different spectrum to a piece of paper under a tungsten lamp.

Right, but then you're ignoring ambient light. Your statement isn't true in a dark room, where the very much does care.

But that's still not a fundamental property of screens, that's a property of a specific working environment.

Screens should not be brighter than ambient light as a rule of thumb, i.e. if you hold a piece of paper next to your screen, the screen should not brighten up the paper. If it does, reduce brightness of your screen and/or turn up the light in your room.

So, a dark room is not an ideal working environment anyway.

> it doesn't really make a difference if the paper was the original emitter of the light or not

I think it makes all the difference in the world.

Aside from power consumption, e-books and e-paper displays exist for this reason.