Boiled milk, yes. But unless you get milk straight from a farm, it's likely pasteurised: Heated to 72 degrees celsius for 15 seconds. [EDIT: I didn't realise how many places allow sales of unpasteurised milk; yikes - I'll be careful about reading labels next time I'm travelling]

> and that there are plenty of people around in cooler climates that have stomachs that usually can handle milk without problem.

The "stomachs that usually can handle milk without a problem" is entirely unrelated from why we pasteurise milk. Pasteurisation does not affect the lactose content in the milk, and that, combined with whether or not your genes makes you lactose intolerant or not is what determines whether or not you handle milk well.