[OJFord]

If you've ever actually seen '47g eggs' it's surely almost certainly because it's been scaled down from a much larger (i.e. commercial) recipe where that would make more sense.

You can buy (in the UK anyway) cartons of egg whites/yolks (separately) - which I think makes a tonne of sense for non-egg-whole cooking, and would love for it to be more common (i.e. cheaper, came out considerably more expensive when I did some 'napkin math' on it a while ago; separating eggs isn't hard/annoying enough to warrant it, I concluded) - but even then you'd surely measure it by volume, not mass.

Eggs by mass is surely whole, shell included; so yeah it's pretty much inherently approximate - as close as you can easily get to 47 (or more likely 470 or 4700) grams with whole eggs.