Price
While you can make generalizations about the kind of people who buy iPhones versus the kind who buy Androids, they’re usually not fair. But, objectively, there does tend to be a price disparity between iPhones and Android devices.
Apple products aren’t cheap. If a user can fork over the money for a $1,000 handset, there’s a good chance that they’re also able to pay $400 for a smartwatch. Android devices are much more diverse in price, which means they’re more attractive to budget-minded consumers who may not be able to justify buying a smartwatch.