Is spiking of drinks really that common? I've only ever seen GHB or Ketamine used recreationally. I've never heard anyone say they'd been intentionally and maliciously dosed, although I've seen people ingest by accident.
It's far, far, more likely that you've had friends who drank too much and then assumed, in the absence of an actual toxicology report or other corroborating evidence, that they were drugged.
Ref: http://www.britac.ac.uk/funding/case-studies/burgess-spiking...
From what I understood it seemed that it was more about 'lightening up and having some more fun,' although I'm not sure how running around all night wondering whether I'm losing my mind would make me have more fun,
No, I doubt that it is because rape is relatively uncommon.
We know that people make mistakes when drunk, and we know that some people use alcohol as a rape-drug. In England it's much more common for people to make bad choices about sex when they're drunk than for a predator to deliberately spike a drink with a drug.
Having a shot glass with whiskey in it and the label "safe" is just weird.
Utilitarianism, as well as "just good horse sense" suggests that finite resources should be allocated to solving problems that cause greater sum harm than lesser sum harm.