Yeah, but in those days we did that because there wasn't any other option. It's not like the colour scheme of the monochrome terminal was chosen for ergonomic reasons.
If anything, amber terminals were easier on the eyes. Or the white on black ones. Those were nice.
When I go outside green is the color my eyes are looking for to relax. Also pixels in the white background emit the maximum energy. One reason Apple introduced the dark mode is the pixels to emit mostly the valuable information and save energy , thus saving the battery life.
The white background is fine for the eyes, so long as the brightness is set properly - minimum brightness for the surrounding lighting with medium-high contrast. IME, this setup in a well lighted office makes a marked difference in eyestrain at the end of the day when compared to dark modes, dark rooms, and high-brightness light modes.
It's totally individual though. Back when we finally got terminals with white background I was very pleased. A co-worker was completely unable to use them though - he had to set the terminal to reverse mode. We talked about it and it was clear his eyesight was completely different from mine. There's no "one size fits all" here, and I for one have problems with dark mode - I see "flares".
This is precisely why I use f.lux[0] on every computer. As the blue light is reduced toward evening, the screen becomes much less bright. Works great for eye comfort and is maybe even beneficial for sleep.
There is no evidence dark mode is better. In fact, human eyes don't have good night vision, we see best in daylight.
Light text on a dark background makes the eye work harder and open wider, since it needs to absorb more light. When this happens, the light letters can bleed into the dark background and cause halation. Our eyes focus better when the iris is narrow.
Additionally, most people are born with some form of astigmatism, a misshaped cornea that blurs vision. For people that have the worst forms of astigmatism, light text on dark backgrounds aggravates the condition. When looking at a light display, the iris closes more, decreasing the effect of the deformed cornea. When using a dark display the iris opens to receive more light and the deformation of the cornea makes halation worse.
On the flip side, dark mode helps with floaters, tiny fibers or spots that appear in a person's vision. These are caused by changes to the fluid in the eye which cause shadows to be cast on the retina. Floaters distort vision in light mode. This condition tends to increase with age.
Also, people with light sensitivity might be better served by a dark background.
I have found that dark mode works best in low light, 100% contrast can be harder to read with more eye strain, reading large amounts of text in dark mode is harder.
It is frustrating when people who work in IT don't take accessibility seriously. Not everybody is young and in perfect health. Both light and dark mode should be offered for accessibility reasons.
Green letters doesn't seem eye friendly at least to my eye. My eye much prefers white on dark grey for emissive screens (LCD, LED) or black on white for reflective screens (e-Ink).
I had the impression that pre-1980's screens were green for chemical reasons not for eye-strain optimization (?)
If anything, amber terminals were easier on the eyes. Or the white on black ones. Those were nice.