Why are placebos becoming increasingly effective only in the US ?

A couple of hypotheses were mentioned in the article. One is that only in USA and New Zealand is direct-to-consumer drug advertising allowed. Another, which seems to have some supporting evidence, is that size and length of the drug trial may boost the placebo effect. The latter point is presumably about the production value of the trial, mandated by increasingly stringent FDA regulations. The apparent cost sells the apparent effectiveness.

I wonder whether these results might be linked to USians sustained high level of religiosity, which is also unique in the developed world.