The broader question is why the technology of classical civilizations was not far better than it actually was, given that they clearly knew many of the basic pr

The broader question is why the technology of classical civilizations was not far better than it actually was, given that they clearly knew many of the basic principles - eg steam power. The traditional answer is "slavery": in societies where copious manpower, in the form of slaves, is so cheap (not free - you still have to feed 'em !), the incentive to productionise technology is vastly reduced.