Higher end displays are already pretty decently calibrated out of the factory, but if you want to be exact you will need to buy an external piece of hardware that will measure your display’s colors and tell you how off they might be.
The author bought a piece of color calibrating hardware that was meant to be open in design and work with Linux, as presumably he wants to support these efforts.
But he encountered a bevy of problems, ranging from packages not updated in a while to things that just plain don’t work as documented, and got frustrated.
Understandable, since on macOS or Windows with proprietary hardware, this would have been a 5 minute process. The author is sad and frustrated that the open source alternatives aren’t there.
In practice, monitors change color over time (much mire common in ccfl backlit monitors, i think) and even shift with brightness, so we have to do it “at runtime”
In addition to that the built-in options for configuration are often very simplified and have a coupling. Low resolution control plus simplified options means that you often can't dial in perfect color reproduction. Hence ICC profiles.
It is physically impossible to get an unique colour space across all surfaces.
Displays aren't calibrated at the factory. To use an LED-backlit display as an example, not every single LED in the world is created equally. Not every LED is going to give off the exact same wavelength for the same current value.
Extrapolate this out to all the other components and this is the reason that your monitor has built-in physical controls for changing RGB/contrast/brightness values to begin with.
Calibration accounts for this.
As for why ICC profiles are used instead of just changing settings on the monitors, the OSD options usually don't offer enough fine-grained control to get things just right. Display makers are typically targeting main-stream consumers so they provide simple adjustment controls.
Standard values of the voltages, currents, timings etc. that are applied to LEDs, liquid crystal pieces and other electronic components of the display in order to get the desired colors are only a starting point; a calibration that measures the differences between devices and compensates them is needed because of manufacturing and accidental differences.
This is true with even the highest quality color critical displays like we use in film/tv color correction ($5-$50k+ for 25" panels).
Spending €100 also isn't an insignificant amount, and for that price I would expect what I'm buying to work properly.
tl;dr : you get what you pay for.
Ok, but I'm not sure how that explains it. You'll need to go into more detail.
We’ve seen this play out dozens of times since the ‘90s, and the startups keep making the same mistakes.
They should at least read their predecessors retrospectives, and strive to make different mistakes.
As for software, DisplayCal is actually very well regarded in pro color and considered one of the only serious three choices, the others being CalMAN and the big dog being Light Illusions.
Better support? Open Hardware means Open Hardware, and nothing more - you get the access to the schematics, documentation, sometimes also right to produce similar devices by yourself. You can expect greater hackability, definitely, but "Open Hardware" sticker means nothing in terms of support or reliability. It might be better, it might be worse, you can't tell.
The price in such projects is directly related to the production scale. How many EX3s, Spyders and ColorHugs have been produced? Open Hardware projects (especially the equivalents of already available non-free devices) are often costlier because it initially attracts only the people who really care about its hackability, which makes the yields low, which makes the prices high, which further strengthens that relation, and the circle is closed.
With userbase kept small, most users usually keep the firmware/software support just right enough to scratch their own itches.
Please remember that hardware is not software, and open hardware comes with completely different set of challenges than free (open) software and when it comes to hardware, you often really need to pay extra for the freedom - not just with your time, like we were used to with early FLOSS, but also with your money. If you choose a project because of its "Open Hardware" sticker, it's really more than likely that it will be costlier and it will be rough at edges, because it's usually harder to roll with such projects than with closed competitors and the ROIs are usually way smaller too. That's just how it is and there's nothing surprising about it; if you care about openness, you have to accept it, otherwise it will never get better.
Source: Am the person that sits in a shed and builds each ColorHug.
Source: Person that designed the ColorHug hardware.
I'd like to add I'm completely appreciative and thankful of what you're doing.