Well I think because what we think of when we think of some of the worst, the inquisition, torture chambers and iron maidens, forced confession and bloodshed of 'holy wars,' crusades, that can dominate, but also because catholicism, for example, is still the largest religon in the world, and did dominate the globe for quite some time. Prior to that, Pagan Rome, though. Which was also dominating, and because they did a hard elimination of other pagan religons, which was their goal, or like in mexico and south america, too. However, china, within its own territories had its troubles even. India with untouchables and brutality with that. I dont think any religon is really 'free' from making mistakes, but others made even bigger mistakes than most.
I wouldnt say as much the 'demand for proof' is big in the west. I would say, demands for 'proof' were created post age of enlightenment because of all the conflicts of science and relgion, but it was necessary, because other religons were demanding 'blind faith' and 'belief,' and to do away with the reasoning mind, which they wanted this more, so as to not lose numbers in a church or group. Because if something does arise in conflict, then a person will struggle with a particular belief. But of course, not all spiritual things can we always expect to get 'proof on,' but reasoning cannot always give us what we need either.