To expand on "literally medieval", it's not just about their legal system and lack of proper rule of law or due process, or about being an absolute monarchy. It's also because the country is literally owned by the royal family, in the same sense as royals in Europe used to own their respective kingdoms, with everyone else getting any property grants from them. Europe still has many vestiges of that in form of "crown lands" etc - but in practice it's the government that is the actual owner there, and monarch doesn't have direct control over it. In Saudi Arabia, he does! So you could also say that, in a sense, all Saudi laws (other than Sharia) are really just rules that the owning family chooses to set for people who live on their property.