[shard972]

Well you have culture first of all, bringing in people from different cultures can lead to animosity and interpersonal conflict at times. Not to mention divise social groups that can occur when you hire alot from one particular country.

That and language, I have worked with devs and testers who just didn't have a great grasp on the english language which lead to a lot of frustration on both sides as we probably used half our jira comments clarifying/confirming what the other person meant.