Much of Cambodia operates on an informal economy basis, that is, the shops are small, family-owned, situated in the family house, not-registered with the government, not-taxed, with no bank account, etc. I suspect a lot of the furniture industry is that way just because of the large numbers of people selling the heavy wooden furniture on the streets. It is probably manufactured in shops in the rural provinces and then hauled to Phnom Penh for final finishing or for sale. Here are pictures of furniture being sold in Phnom Penh.