Even in the US, autopsies are not always performed. Ima quote WebMD because I'm bone idle:

Although laws vary, nearly all states call for an autopsy when someone dies in a suspicious, unusual, or unnatural way.

Many states have one done when a person dies without a doctor present. Twenty-seven states require it if the cause of death is suspected to be from a public health threat, such as a fast-spreading disease or tainted food.

According to a 2012 DOJ report, only 8.5% of US deaths result in autopsy.