Notes on Vietnamese traffic:
There are easily 60 motorbikes per car.
Motorbikes can hold generally up to 5 people at one time. If you use a childseat, you can generally only fit 3. Including the kid. Most drivers have helmets and masks to protect from injury and pollution. Sometimes, drivers are nice enough to provide one or both of those to their passengers:

You may wonder what they do during the monsoon season - whatever they have to to keep themselves dry.

It is clear that motorbikes are popular not only because they are cheaper, but because they are so much more maneuverable. There is also no place to park cars anywhere.
There is actually no place to park motorbikes either, generally... unless you count the sidewalk. Motorbikes are permitted to not only park on the sidewalk, but drive on the sidewalk. The curbs are even inclined to make this easier.
What this means is, the only place for pedestrians to walk, is on the street. The trouble is, by doing so, you've effectively become part of the flow of traffic. On a wider street, this is inconvenient, but when you are sauntering down a narrow market street that is lined on both sides by women selling fish and meat, having a motorbike beep at you and push you into a stall of raw meat is, well, irritating. After a while, you just start yelling, "yeah.. yeah" dismissively like a grumpy New York cabbie every time a motorbike nearly rides up your leg. Again, if only I could show you the video I took to illustrate how maniacal this traffic is. Here is what mothers who are taking their toddlers out for a stroll look like - see the traffic whizzing by them? They are actually pushing the strollers on the street:

This is what kids have to do while walking down the street.. keep in mind.. this is only going DOWN a street.. not across it. We'll get to that in a minute:

Crossing the street requires a total leap of faith. There are "cross walks" but those are totally ignored by all traffic. To cross the street, you essentially have to just start walking into the traffic. At first, this is extremely daunting - you have hundreds of motorbikes going by at about 20-30 miles an hour. It is definitely a little like that old 80's video game, "Frogger." The rule is simple... you walk across the street in a steady pace, watching the vehicles around you, but you never, start to run. This confuses the drivers, apparently, who are trying to drive around you as you cross their path. Tourists, upon arrival at a major Vietnamese city inevitably face the traffic situation with understandable trepidation. This is why you will often see a bunch of westerners standing on the side of a street paralyzed. The issue is, even if you think you've looked both ways and are sure that at least for the next 5 seconds or so you will not get hit by anything on the road, that doesn't mean that a motorbike driving on the sidewalk won't hit you while you are standing there. The good thing is, if you are a girl, a Vietnamese woman (usually a much older woman) will inevitably take pity on you, take your arm and help you across. Never thought an 80 year old woman would ever help ME cross the street at my age, but there you go. Usually they do so quite happily with a giggle and a smile.
I'll close this post with an artsy fartsy traffic shot. It wasn't meant to be this artsy, but it was the only one I got of what a florist looks like while making a delivery in Vietnam at it is really the site to see: