Saudi's are 'priviledged' when it comes to democracy because they are perhaps the most significant ally to the US (and us) in the region.
Plus they buy insane amounts of weaponry. It's only 1% of UK exports but equivalent to around half of our R&D spend on Defence. The percentages are similair in the US, but of course they spend far more on the military than we do, in total, and per capita. Saudi are the second largest importer of arms globally (after India) and over 80% of their imports come from the US and UK.
This is perhaps why Germany took a stance against exporting weapons to the Saudis in response to the Yemen conflict, and we didn't.
Yemen is a case in point. It is largely fought conventionally.. Saudi Arabia spends by far the most on weaponry in the middle east.
Iran, for example, spend a fraction of the amount on their military. Instead they frequently use proxies and other methods (terrorism/asymetric warfare), as do many others in the region.
Apart from that, western countries rely on the Saudi oil supply, but moreso their position within Opec. With 15% of overall supply, they can break that market with ease.
Oh yeah, and Saudi was Donald's first Overseas trip. And Kushner is the Crown Prince's bestie.