Often, whenever the Muggles see magic or any kind of supernatural weirdness going on, they'll refuse to believe they saw such a thing with their own eyes and just go on with their daily lives. Thus, the Weirdness Censor is the perfect way for a Masquerade to go around unnoticed because ordinary people won't care much about magic as long as it doesn't intrude on their sense of normalcy. But sometimes, there is no need for the Weirdness Censor because the weirdness just plain happens often enough to be commonplace. In such a setting, magic, Aliens in Cardiff, and hyper-advanced technology is all so ubiquitous that people would be much more likely to notice when strangeness fails to happen. This, in essence, defines a Plausible Implausibility: some event or thing that should be strange isn't because the nature of the setting renders any inherent strangeness moot.
Hello, Unknown Troper. You'll need to get known to lend a hand here.