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’.