Why is there no universal power supply?

Like everyone, I have dozens of different power supplies, one for the PC, one for the laptop, one for the monitor, etc… And a neat cable tangle at the desk.

Why is there no power supply unit with different outputs (with different voltages) to which the different consumers are then connected separately?

Or is there and I just didn't find it?

Since these are too many tensions: No, there's not. Although it used to be common for the PC power supply to have an output for the monitor, I would not currently know of any power supply that still has this feature.

That would be totally inefficient because 90% of the outputs remained unused.

Buy a special basket ("cable basket"), which you mount under the desk, and put in the cables and power supplies. Problem solved.

Well… There are some approaches in the right direction with USB 3.1 GEN 2 and USB-PD.
You want to standardize as much as possible (at least up to 100W (20V 5A)).
USB4.0 is already being planned. Then Lightning etc. Should also be integrated.
At the moment, however, the device manufacturers are shooting against it.

If you e.g. Buy a cell phone that has a "universal" interface…
And a charger from another manufacturer…
Let us assume that the mobile phone suddenly flares up when charging.

Who is guilty? Who is paying?

In order to protect themselves from this problem, all manufacturers of cell phones want e.g. Own power supplies that you can trust.

However, it will still take some time before we have a 100% uniform charging standard.

Because every manufacturer has provided its own power supply for its device. Every manufacturer also uses different voltages and currents for their devices for cost reasons. How should a universal power supply be designed to meet all requirements? And that the manufacturers coordinate with each other - you can wait a long time for that.

The disadvantage of a universal power supply is that all other connected devices can't be used if the universal power supply is also put out of action by a defective connected device.

It has something to do with electronics.
Let's put it this way: You don't want to charge your smartphone with the same power as your laptop / PC and vice versa. Either you grill weaker devices or wait forever until stronger devices have been loaded.

Was also the subject of the last heise show: