British Lamb? Or New Zealand Lamb?

I was shopping in a supermarket the other day, buying lamb liver and asked to the shop assistant to reserve some of the liver for me to buy later. He replied:
-Which country's lamb liver you prefer? New Zealand or British?
Me:
-What is the difference?
Shop assistant:
-Well, New Zealand lamb liver is cheaper.
What do you think my choice was? Of course New Zealand one. If both of them available in front of me and one is cheaper than the other, of course I will go for the cheaper option (Yes, they were both equally similar). If somebody wants me to consider on for some environmental issues and go for the 'local' product, my opinion is, it shouldn't be left to the consumers at first place. It should be worries of government's with the regulation on importing/exporting subject. That's the one thing about this ridiculousness (I guess this word doesn't exist).

Second thing is, how come NZ lamb is cheaper than the British lamb? It's produced in a country that at the other side of the world. What about the cost of the transport, what about the cost of production? And it means that they can make some profits despite to all of these.

If it is possible to produce cheaper farm products and still make profits, what is wrong with the farmers in England or shall I say with the goverment?

Any answer to these questions?..