Phnom Penh’s traffic makes a good analogy for Cambodia: exiting the airport, my tuk tuk driver turns into a traffic jam. As in the past, on our left the snarl of old tuk tuks, acrid motorbikes and clapped out vans are going nowhere. On our right, a mess of roadworks offer pain but also progress. And just beyond, as if to soon be within reach, is a BMW Premium Auto showroom with new, “cleaner and greener” cars …