If all 3 regions complied with ICH rather than having developed their own versions, that would be a start. Also, in the EU if all regulatory agencies complied with the spirit of EU legislation rather than 'gold plating' with additional opaque requirements and confusing so many, that would help as well. Would be good to have common international principles for what a regulatory agency is meant to be and do? That would help. But reality is there is no integrated global regulatory system.
I agree Brian. major factor is different regulations for registration like, monographs, guidelines, clinical requirements, etc.
although ICH has harmonised the registration format, but still there is lots of different requirements, which hampers the timely development and approval of the products.