Alright, time for a blast back to the past.
As someone who's continuously roleplayed only spooks on the server for the past 7 years, I can think back to the days of Axios and Atlas and immediately recall how a younger me had some extreme issues with the spook testing that existed in those days. Many of you were not around in those days, spook roleplayers and non-spook roleplayers, and so you might not recall how things existed in those days pertaining to the state of spook testing.
As it was, in those days, both Clerics, Paladins and Ascended existed, each a form of holy mage that could test for spooks in their own individual ways. Compared to today, they had complete free reign to be able to easily identify any spook without issue.
Today, in contrast, Templars and Paladins cannot specifically identify spooks in the way that they could before. The energy that Paladins produce hurts everyone without any kind of specificity, barring them from being able to test people. Templars, as far as I am aware, are not able to produce any kind of specific spook testing beyond the mild discomfort that spooks feel in proximity to their magical hearths. This is a VAST improvement.
Each of these holy mages were able to, and thus did, erect pyres of holy fire in each and every gate house that existed on the continent.
Simply stated, if you touched that fire and you were a spook, you would feel immense agony. If you were not a spook, you'd feel some comforting warmth. Another vast improvement is the complete lack of these pyres today. They were chronically used, and you would be asked to place your hand in the fire every time you entered a gatehouse.
Not only were holy mages able to SPECIFICALLY test for dark magic in people without fail, but so were voidal mages.
I was once caught as a Dark Mage because a Voidal Mage was able to utilize a certain ability to view my magical aura, which, as a spook, was black. They were then able to deduce my status as a spook and sic the guards on me. I know this doesn't seem super relevant, but think about it - if all of these options were around back in the day for people to specifically test for dark magic without fail and effectively curbstomp any attempt at villainy within their cities, why are people still complaining to the same degree regarding spook testing as they did back then?
Aurum testing has always been around.
Whilst earlier on, there were more efficient, more successful ways at detecting Dark Mages, these have since been eradicated, obviously. The reason for the prevalence of the salt test and the Aurum test these days is simply because there is nothing else, and nothing better, that people can do to try and stop the forces of evil from entering their homes. It is a mundane, accessible option, but not one that always succeeds. It's been around for years.
The Aurum test inadvertently exists to make villains think with a little more intelligence.
There have been some very valid points from both sides of the argument that have already been raised, such as by @SethWolf and @Unwillingly and @Islamadon, but in all my time as someone who's always enjoyed playing the villain, I've always believed that this test has simply existed as something for people to be able to think more intelligently about how they go about their villainous activities. Whilst it is lazy to test in this way, it is equally lazy to not think of the best way to avoid it. I personally have found that this form of subversion is one of my favourite parts of being a villain. There's always going to be someone who's going to try to get in your way. Your job? It's just as much about getting past them and the problems they pose as it is causing the villainy in itself.
I'm entirely open to criticism about the way I think, and I'd be happy to debate it, either here on the forums or in my Discord DMs. My Discord is childneglecter. Hit me up if any of you want to talk about it any further.