Apart from the need of roasting coffee close to where the demand is to ensure "freshness", the other main reason that most large roasting operations are in Europe and US is "mixing". Most commercial coffees that you buy at a supermarket or even at coffee shops are a mix of various varieties. The provenance and ratios in the final mix change continuously to adapt to different taste (that may vary from harvest to harvest in the same estate), yields and prices, with the aim of maintaining a stable taste year on year and a stable cost. So even large coffee producing countries can not produce the right mix, and usually choose to penalise coffee imports (with duties) to protect local farmers.