[fatfingerd]

The channels to scan vary with country based on government regulation of frequencies. Normally, a full list of rules is accumulated for each implementation so it could be used globally.

A possibility is that Google thinks they will avoid pointless legal risk by not having support at all for countries they "don't need" or to prevent unauthorized exporters. This would be quite silly because travelers expect to roam with their devices.

Another possibility is that people are using other imported hardware that is not configured to the current country and selecting channels not actually allowed in the country. This is usually only 1 channel in a dozen so seemingly unlikely, though congestion algorithms prefer a channel that no one else is using..