Fantastic blogpost by @jasoncrawford on why the bicycle wasn’t invented earlier. We can ask similar questions of many other technologies. My favourite is the flying shuttle on looms. Another is mechanical telegraphing systems like semaphore. https://rootsofprogress.org/why-did-we-wait-so-long-for-the-bicycle

On semaphore: the first concerted attempts at such systems appear in France in the late 18thC using windmill-like structures. Why so late?! Before that, all you get is the lighting of the beacons scene in Lord of the Rings - and that’s just a single message.

Then during the Napoleonic Wars in Britain you see absolutely loads of flag based systems. Again, why not earlier? My favourite is this one, the “homograph”, devised by Lieutenant James Spratt. As he put it, “every man a signal tower”.

Perhaps unsurprisingly, the system that’s adopted by the British comes from an Admiral, with the glorious name of Sir Home Riggs Popham. His system is the one used by Nelson at Trafalgar to say “England expects that every man will do his duty”.