When I was a student one of my mates was going on about the superiority of the metric system and how he wished the UK would adopt it fully rather than the heterogenous mix we actually have. The football was on in the background, and shortly after a goal was scored he exclaimed 'that must have been from thirty yards!' Personally I quite like the fact we use both, it underlines that our human systems of measurement are arbitrary rather than baked into the fabric of reality.

I'm too old to be a zoomer and too young to be a millennial, but I'm more or less bilingual with unit systems. Useful for a European who deals with the US often!

I'm a year older than Conway and have never heard people using yards to mean anything other than a concreted or paved area, even in rural settings.

Maybe posh horsey types are different, but even they're mostly concerned with furlongs and hands and suchlike.

(Not wanting to disparage Conway or his work - it's likely that, as gp suggests, his choice of measurements is simply due to the historic source material)