I am actually surprised you asked the question.
You basically gave yourself the answer.... the big corporation environment is a niche.
Big corporations hire usually people having a specific set of skills, including a reasonable level of Business English.
However in the vast majority of countries, SMEs are the backbone of economy (i.e. in Europe you have around 20M companies, more than 95% are SMEs)...and in them the knowledge of English is not common.
Excluding some areas (i.e. Northern Europe) the knowledge of English is very basic and that would be a major barrier to do business.
Last but not least, to reply to Rodrigo ("doing business between Germany and US? Sure, not much a barrier"), there is a lot of hype about several countries "speaking English well"....I can speak for personal experience....stay a while in Germany and you'll soon understand what I mean.