rounser said:A quick review of the monster manuals might actually recommend this course of action. I assume you can count the number of good, non-savage races on fingers and toes. The rest are potentially hostile, or actively hostile and unable to be reasoned with.
But you're right, D&D people act as if they're in a pseudomedieval world rather than a "D&D brought to it's logical conclusion" world, and seem largely oblivious to the sheer number of monsters wandering around the landscape. For their part, the monsters seem to have an unspoken agreement to leave human towns and farms alone until a plot point comes along.
It doesn't stand up to scrutiny, but the alternative to handwaving such stuff is probably far worse.
Only very few monsters in the MM are civilized like the Dragonborn are. Generally, if they carry manufactured weapons/tools then you need to investigate further. And all civilized monsters in the MM which are evil deserve this bad reputation. Dragonborn on the other hande are not.
And as I said before, the first contact between Dragonborn and Humans was several hundered in the past. By now humans know that Dragonborn are no monsters.