Most computers in Turkey come with FreeDOS preinstalled because there's a law that states all computers must be sold with an operating system. FreeDOS turns out to be the cheapest and easiest.
That's why you don't let people who have never touched a computer write tech laws. You get results like this.
Those types of laws aren't all that bad.. they got us this: https://segaretro.org/Dottori_Kun
The computer is not very usable without an operating system. I think it would be reasonable for the computer to have Forth or BASIC or something like that in ROM, like many older computers do, so that the computer is usable without an operating system (but that you could also install an operating system if you wanted it).
I wish that was the case where I live. I'm looking for a new laptop and the mainstream ones still come with the Windows Tax.
Russia has a similar law and yes computers with FreeDOS are also a thing. Alternatively, you're entitled to get a refund for the Windows license by having your hard drive wiped and license sticker removed.
Is there a reason they don't go with Ubuntu or something like that instead?
The really weird case is where the computer isn't actually compatible with DOS, so they put in a locked-down Linux distro that emulates FreeDOS.