>Apple has low volume sales?
In comparison. Android phones (in total) outsell iPhones because they are cheaper/more affordable. Sure Macs and iPhones may sell more than an individual non Apple brand, but collectively all together, the non-apple brands outsell Apple.
But it is certainly true that making high quality products doesn't necessarily mean low sales.
Apple has 70% of sales share and 80% of usage share in the US. Your comment is true world-wide, but this thread is about the US.