They've had them in Holland decades ago. Tried them once, was the craziest movie experience I've ever had and didn't feel like repeating this ever again.
From a programmer's perspective, I think everyone should try them once. It's like commenting out a portion of the code to see the effects as part of debugging. It's neat to be like, "Oh, if you just turn off the image stabilization, the walls look like waves, and then the pattern matcher takes over and goes crazy."
I think this is an important distinction many people who are not familiar with the matter miss, psilocybin is not a party drug. I would say psilocybin is closer to say ayahuasca than it is to MDMA or other similar things. A good analogy I once heard is that on party drugs, you're figuratively behind the driver's wheel, whereas on psilocybin you're along for the drive and you'll see where it takes you.
I think this is a misconception about psilocybin and drugs in general. Just like "the dose makes the poison," the dose determines how much control you have. Small doses of acid/mushrooms are very common among partying festivalgoers.