KSA is protected by their wealth in the international community. West is highly dependent on Saudi petroleum products and US especially considers geographical and strategic importance of Saudia vital to their interests in the region.
In the region itself which is populated mainly by Sunni Muslims, Saudia is revered just for the fact that they hold the two holy cities of Mecca and Medina. General populace never believes anything bad about them and considers them just as holy. An attack on them will be considered an attack on Islam itself by many, creating a very dangerous situation.
Iran and Turkey are no saints either. Turkey under the leadership of Recep Tayep Erodgan is not the Turkey that we know. They are actively involved in Saudi led fanatic alliances. Iran is well Iran, twin sister of KSA but less uglier.
As for UN, it is a puppet organization, what do you expect them to do? Recently KSA got a seat in the UN human rights entity. A Saudi Ambassador has been elected chair of the Human Rights Council with of course help of the UK. As Hillel Neuer puts it:
It is scandalous that the UN chose a country that has beheaded more
people this year than ISIS to be head of a key human rights panel.
Petro-dollars and politics have trumped human rights.
Justice is for poor, losers and the weak. Rich, victors and strong always get away with everything. It's always been this way.
Nazis got Nuremberg trials for their crimes but were the Allies ever tried for Dresden bombing, hamburg bombing, Battle for Berlin, Japanese nuclear massacre?
Saddam got hanged for his crimes but did his US mates got the same?
Serbian President faced war crimes tribunals for Bosnia but will NATO face the same for Serbian TV bombing raid? Will Barack Obama answer for drone murders and recent hospital bombing?
It's always been this way.