Building a 3D printer is easy. Getting the details right to build a great 3D printer is hard, as this is where most companies fail. Why?
For example, on this printer, the bed is a three-point mount (two wheels for adjustment at the front of the printbed) and the printer's bed levelling dialogue doesn't show the height difference that needs to be adjusted (which most 3D printers do). It does show how much it needs to be turned, and the bed levelling wheels have 1/8th turn indicators, making it easy to get it perfect.
In short, instead of an arbitrary number like 0.3mm that has no meaning to the user, they tell the user to turn this knob 1/4 of a turn. An instruction the user can follow.
** Why is this so outstanding? It doesn't cost much, but it improves the user experience. Are companies blind to these improvements because the engineers are experienced, or is there a lack of testing during development?**
By the way, years ago I did such a fix/modification myself on a Tronxy XY2 pro by adding indicators on the wheel for 0.2mm height difference so I could convert the number to rotation: https://www.printables.com/model/301670-replacement-bed-leveling-wheel
How much do you need to turn the knob for 0.3mm? Most people don't know the answer so they make a guess which is likley wrong.
If the firmware converts 0.3mm to 1/2 rotation it is clear what they should do. This particular printer probs itself after the adjustments and if it isn't right it shows once more the dialog/instruction with the adjusted rotation value. After 2 rounds, you would already have accounted for the manufacturing tolerances.
This process can be ontop of ABL and z-offset dialog (eyeball it with a shim, testprint, tell the printer which looked the best, the firmware knows what z-offset was each of the 5 prints/lines).