Making people happy is surprisingly easy; all it takes is a couple of electrodes inserted into the brain. So if that's the only bar that you have, the Amish are way overthinking it.
In theory yes; in practice, it's beyond our technological capabilities at the moment. A better alternative would be drugs. And honestly, it's our "universal culture" that's more susceptible to this failure mode.
I recall reading about such experiments done on rats, and that was at least a couple decades ago. Is it really beyond our technological capabilities? Note, I'm not talking about electrodes to induce dreams or some such; just a simple direct electric stimulation of the pleasure centers. Presumably, the resulting sensation is that you wouldn't know why you're happy - you're just happy.
Direct electric stimulation of brain (implanting electrodes) is simple only if you don't care if the subject has a risk of fatal infection, and if performing literal brain surgery is cheap and routine, as it is for mice/rats (again, because a risk of death or brain damage is acceptable).
Yes, we can do that, but that would be complicated to do it safely on humans - compared to that, a lifetime supply of drugs is cheap and simple.