One of the concerns that one can have regarding the use of RCTs for evaluating policies is that while when done in small scales, the RCTs may show the result in one direction, scaling the policies may involve general equilibrium effects that may possibly make the relationship of interest nil or even the opposite of what was found in the small scale RCTs.
Several possible examples, intuitively, can be thought of immediately.
But I would like to have some real world examples where this has happened. Links to any relevant papers that demonstrate this would be helpful.