The inverse (Windows deliberately not looking like Mac) seems likely to have been at least partially responsible. Apple were litigious about their design langua

The inverse (Windows deliberately not looking like Mac) seems likely to have been at least partially responsible. Apple were litigious about their design language - with the ‘trash can’ being a particular point of contention. Microsoft were probably at least a little cautious about looking too Mac-like. Indeed Apple in the end did sue MS for stealing ’look and feel’ elements in 1988 (literally the context in which the term look-and-feel was popularized), ultimately unsuccessfully - except for the trash can being recognized as distinctive enough to not be allowed to be copied, leading to Windows’ 90s classic ‘recycle bin’.