Yes...sir...u r right about double deckers tour bus. In US, Canada,France,Germany etc.
They don't use this kind of bus, only in UK that they used as a city bus though, not tour bus with flat bed. Lao used it bcoz they thought it was a fancy kind of tranportation from Thailand, they don't even think about the hazard of it. On top of that the rule of the road is terrible and the road itself is unsafe.
In the US they have very strict rule & laws of the road and safety comes first. In Lao, nobody cares, they just want to gobble up the money that's all. I bet if the accident happens 4 a few times, they still wouldn't change anything.