The last two paragraphs of a DVB article explain the closure of the “Friendship Bridge” according to the Thai govenor of Tak Province:
Thailand’s Foreign Trade Department estimated in October last year that around $US3 million was being lost each day due to the closure of the bridge, the main land-crossing between the two countries. In 2009 trade through Mae Sot was worth about $US860 million, nearly a quarter of the total annual bilateral trade.
Perhaps as a result of the bridge’s closure, as well as attempts by Thailand to curry favour with the junta in return for winning lucrative investment contracts, Thai policy toward refugees has become stricter, and some 10,000 Karen who fled earlier this year have been forced to find shelter in makeshift camps along the river, with little access to food and healthcare.
Meanwhile the military on both sides of the river profit, more bribes. Big ones for the important soldiers, who can help with smuggling the significant loads, small ones for the average grunt, but a nice addition to the family budget. The bridge could stay closed as long as the two governments are controled by the military.