Cashflow is hard ... On the one hand you must pay 200,000+ employees everywhere in the world at regular intervals without fail. But on the other hand, the cash to do that is tied up in various places, it's in a different country, it's in various interest-bearing bonds or shares that cannot be redeemed quickly, or it's even in future revenues that you've not received yet. And it wouldn't be efficient to have a massive cash float on hand in country-specific bank accounts, when that money could be invested profitably.