I'd have assumed that Pratchett was an equalitarian, "The souls of emperors and cobblers are cast in the same mold" sort of thing, yet in Mort we see that kings don't get the scythe treatment, they get a sword instead. Am I just misreading this, or does that not argue that kings are, pardon the pun, a cut above the common man? by later books, once we're in the discworld proper and not the proto-discworld we see in mort and earlier novels, there's a bit of a tendancy to argue against that... or so I thought. Maybe it's just vimes bitching to himself though.
Hmm, maybe kings are treated specially, but then so are wizards and witches, who are sure Death will personally turn up for them, so are rats, as they have their own Death... I don't think royalty has much of a special treatment, the few we see are usually depicted as being as stupid, clumsy, clueless, and generally human as any other character, in fact, they are quite often even more clumsy, clueless, etc. (see Verence)
I thought things like that were shaped by the belief of the people, not by the actual nature of things. I would argue that kings get the sword because Discworld people believe that kings should get the sword, not because Pratchett thinks they should.