In the US, you are literally a target. Road rage is a thing. Someone turning left or right on you happens all the time. In Vietnam, cars turn really slowly and usually in a predictable manner.
Now, the issue is that when things go wrong, they go really wrong. Vietnam has one of the highest rates of road deaths in the world [1] [2]. I think these numbers are actually low, because not all deaths even get reported. Also, not everyone dies... non-fatal accidents happen constantly here.
The other issue is that this is a relatively young country for people behind the wheel of a car. Cars have only been widely accessible here for the last ~10 years and it is growing. The level of skill for drivers is extremely low, the education testing is a joke. There is constantly videos of people driving their car/bus/truck through a group of people, house or off the road because they mistake the gas for the brake. Or even worse... side effect accidents... [3]
[1] https://e.vnexpress.net/news/news/traffic-accidents-kill-ove...
[2] https://tuoitrenews.vn/news/society/20180220/179-killed-in-t...
[3] https://www.facebook.com/vieclamtaixelaixe/videos/1972940609...
And majority of expats get by fine without motorcycle racing experience, the biggest issue is as always driving while drunk.