Why all computer casing & cables are black?

I have a bunch of SATA cables in junk drawer: some black, also red, blue, orange and grey

You might be looking at the casing and cables in the dark. Without light, what's left is dark. Try turning on a light.

If you're using a camera, try switching from B&W to color mode. If that doesn't work, check if the monitor has the power turned on.

If you're doing this at night, try again after the sun rises. If you're wearing sunglasses at night, see if removing the sunglasses helps. Also check if you're wearing tinted glasses, blinders, or dark glasses for the blind.

If you're wearing smart glasses or auto-darkening welding goggles, check if it's turned on, properly adjusted and if the battery is fully charged.

Why isn't the default color WHITE? Or red? Why black? :)

Because the outer sheath of cables needs to be UV resistant. That's done by adding carbon black to the mix during manufacture. Carbon black has and important attribute. It is cheap. If you want a white outer sheath, the manufacturer would likely add titanium dioxide, which costs more.

"The Roles of Carbon Black in Wire & Cable Conductor, Insulation and Jacketing Applications"

It used not to be black.

I remember when computer cases and many cables were almost all beige.

I guess it's mainly fashion.

I beg to differ. All the early POTS phones were black. In 1959, Ma Bell introduces the "princess" in a multitude of colors. It was mostly a flop because AT&T wanted a too much money for the colorful phones. Because there was no competition, the telephone monopoly had no interest style, fashion, trendish design, elaborate options, etc, Ma Bell offered exactly one color... black. Same with the early Ford automobiles. You can have any color you want, as long as it's black. In 1968, after the phone monopoly was broken up into regional "baby Bell" units and independent hardware vendors were allowed to provide "foreign attachments", one of the first thing offered were colorful (princess) phones.

There was a good reason for pushing beige colored computers.

"I am stuck in a Beige Bubble"

Sorta, kinda, maybe. Fashion has it's place, but it's a bad thing upon which to base a product design or company image. I'll make it easy. Just follow the money. If there's a financial reason for doing something that doesn't seem obvious, you have just discovered the answer.

You guys and gals remember the flag of islamic State? It's black.

Fossil fuel and coal are also black.

Does this ring a bell? Meow.... :)

Not the case. Nothing 'smart' has ever emanated from that source.

When they were built by hand, rubber sleave was typically black.

More modern cables in grey PVC.

It took UL a long time to accept that color additives didn't necessarily affect flammability or temperature class. Color of insulation material is still specified, to this day.

RL

The 3rd Abbasid Caliphate had a black flag:

Automobile tire manufacturing is the major user of carbon black for increased durability and UV protection. Just about anything that contains elemental carbon is going to be black.

Not really. What's your point?

More of the same...

Black is beautiful:

All the villains in the early movies and TV shows wore black.

Black cars have a higher resale value:

Black cars attract automobile accidents:

and so on...

Now you're on a few more watch lists

wrong... not all fossil fuel is black, gas, a fossil fuel, is invisible

also, there is no "and" in that, because coal is a fossil fuel.

Are you saying Man wai Chung is going to electrocute himself?

Nah, I'm sure he's that paranoid he wears flashover suits everytime he turn the kitchen light on.

I think he's seen way too many conspiracy movies from hollywood, next thing he'll be complaining about is that low flying black helicopter above his place at 3AM