I understand what you're getting at. In this particular instance, I'm not sure there was enough sand being contacted by the club (the replay showed maybe 1-2 grains of fluffed-up sand being contacted) that would've been detected by the player. I'm inclined to give her the benefit of the doubt when she says she didn't know.
That said, as an amateur who actively competes in tournaments throughout the course of a season, I'm personally aware of that type of situation. I take extra precaution when I'm in a hazard of any sort by giving myself an additional 3-4 inches of leeway, just to make sure I'm nowhere near grounding my club. When I'm practicing my putting stroke aside of the ball - I make sure I'm far enough away to not inadvertently make contact with it. When I'm grounding my putter behind the ball and taking my stance - I make sure to give myself 3-4 inches of room between the ball and the putter face, just so I better ensure that I don't inadvertently touch the ball or cause it to move.
I'm not competing for majors and millions of dollars. I'm competing for pride and a chance to win maybe a hundred bucks of pro-shop credit. Yet I still exercise a little awareness in those situations.
Nordqvist was just careless in that situation, and although the penalty seems extremely harsh for something that seemed so trivial - she understood the rules and agreed to play by them. And kudos to her for accepting responsibility and taking it on the chin. There've been a few instances in the past when this has happened (Wie) and it wasn't accepted nearly as well, if memory serves anyway.