Every satellite has a 'footprint' relating to its reception area. Here, for example, is the footprint for the Astra 2D satellite, which provides many UK viewers with their satellite TV services:
http://www.digitalsat...astra2dfootprint.html
You'll see from that illustration that a 60cm satellite dish is good enough for reception across the whole of the UK but viewers in northern Italy, hoping to pick up signals from Astra 2D, would need a massive 3m dish.
Astra 2D and the other satellites providing services to the UK provide hardly any channels broadcasting in Asian languages, which means that those seeking to receive such programming must get them from other satellites. Those satellites don't have their footprints centred over the UK. (Hotbird 6, for example, has its beam centred over France). So that means viewers will require a larger satellite dish than those used by people watching Freesat or Sky. Those dishes could be any colour but, presumably, the most popular models are made in white.
Chris