Because the traffic is not the same as Viet Nam Thai. Viet Nam does not have an official car back. The u-turn of Viet Nam to the back arrow or cut in front of each other by using the horn signal.
Because the traffic in Vietnam is not like Thailand. Vietnam does not have to turn official. The turn of Vietnam will cut back the back arrow or by using the horn is.
Because of the traffic that Vietnam is not the same as) Vietnam no U-turn officially Reversing of Vietnam are back in optimized patching or cut using a horn signals as the core