It's not, really. They both suck. Both regular PCs and the RPi need piles of proprietary code to work, and a regular PC is arguably a lot more complicated and t

It's not, really. They both suck. Both regular PCs and the RPi need piles of proprietary code to work, and a regular PC is arguably a lot more complicated and thus has a lot more proprietary parts. The difference is mostly that PCs have decades of history of having an openly documented abstraction layer below which all the proprietary stuff is piled on, so it looks more open than the RPi which makes all the proprietary stuff more obvious and in your face. Among ARM SBCs, the RPi used to be one of the least open ones. These days things are slightly better. It's still not great, but it's also hard to find alternatives that are much better. Nvidia Tegra boards are pretty good; you can run those with fully open source firmware these days, at least the X1 (the last bit missing was the DDR4 training code, but that's been reverse engineered now). It's still hard to get all the pieces working with "clean" open code though.