Traffic Laws

Driving laws in Asia are much sparser than in many parts of the world. During rush hour in Hanoi, for instance, the sidewalks become extra driving lanes, and the roads can be a very dangerous place. The likelihood of your vehicle being hit is much higher on the street than on your property.

Enforcement

Driving laws are rarely enforced. In many countries in Asia, traffic cops are taken less seriously than other police forces, and the driving laws that do exist are not enforced. Another law that's not enforced? Insurance. If someone hits your vehicle, they're not likely to leave a note.

Consideration

Streets are narrower. Many Asian cities are thousands of years old, and because of that, the streets are narrow and crowded. Leaving your car parked on a crowded side street not only increases the likelihood it will be hit, but it's also rude.

Theft

Non-violent crime is higher, especially in poor countries. While murder rates are low in most of Asia, non-violent crimes like theft are often very high, and often ex-pats are targeted. People in desperate need may see your $7,000 Vespa as an extravagant expense. Leave it on the street, and it's much more likely to disappear.

Other Options

Consider your surroundings and your other options. If you live in Singapore, your street-parked vehicle is probably much safer than if you live in Vietnam, where theft and crazy driving is common. For ideas about where to park your vehicle, do as the locals do: park your motorbike in your living room. It may seem silly, but it's a much safer option. Many shops also offer a security guard to watch your vehicle in their parking lot. There's a nominal fee, but take advantage of the service.

Source:

"Vietnam: Traffic Safety"; U.S. Dept. of State:

"China: Traffic Safety"; U.S. Dept. of State