What time is it? Watches and horology

Purely because it wasn’t a thing until digital typesetting technology made it a thing.

Fonts, as in digital font files, widely adopted the standard of monospaced numerals early on because it allows for columns of numbers to line up. By default most cheaper fonts, system fonts especially, still do that and the most visible artefact of it is too much space around the 1s compared to traditional typesetting or lettering practice.

Vintage watches - really anything up the 90s to be honest - actually rarely used fonts as we know them. The dials were always hand-lettered by an expert craftsman and reproduced photographically (by screen printing or transfer printing). The technology didn’t exist to arrange type in different sizes, at different angles, based off a font. All metal type fonts were conceived to print blocks of lines of text onto paper. Watch dials are a very different problem.

So it’s only nowadays that you get designers (who are much less highly trained, typographically speaking) attempting to lay out complex lettering using computer software and completely failing to have any sensitivity to the specific challenges of dial design.

One of the other things that’s obvious on that Longines chrono is the numbers getting lighter/thinner as they get smaller. That’s digital scaling of the letterforms. Someone rendering those numbers by hand would adapt the shape of the characters to the available space while maintaining more consistent visual weight (especially in the thickness of the lines).

The overlapping numerals simply wasn’t possible in typesetting before photo type in the 70s and really didn’t happen at all until the 90s when digital type made it possible and everyone went crazy experimenting with extreme letter spacing, scaling, rotation etc. And up to then it would have been considered extremely bad practice, bordering on heresy.