Campag launched their 'piccolo' brake in the early 1970s. There had been short reach brakes before then, but the others didn't have a major impact on the 'average road racing bike' but the campag brake did. For about a decade they made 'standard reach'' and 'piccolo' brakes in most of their groupsets but then they discontinued the (longer) standard reach brakes, at first in the more expensive groupsets, and later in all of them. Shimano likewise made both short reach brakes and longer 'standard' reach brakes for most groupsets in the 1980s (but not all) and by the time dual pivot brakes came in, what had been 'standard reach' brakes a decade before were now referred to as ''long reach' and what had been 'piccolo' or 'short reach' were now referred to as 'standard reach'. Indeed they were the only ones you could get in many groupsets, typically with a maximum reach of 49-50mm. If you wanted a longer brake than that in a good groupset, it had to be shimano and it was usually a 'non-series' part, hence BR-R450 and BR-R650 brakes.
So the assumption appeared to be that if you were a keen racer you would want to have the option to fit campag brakes on your training bike (even though they appeared to have lost their minds in some respects and were no longer making parts that were actually practical, or sometimes worked at all) and that this would be more important to the average rider than the mere matter of mudguard clearance and tyre section width. So for quite a few years training bikes and some others (eg like the Mercian KOM model) came with ~50mm brake drops and this would allow 23mm tyres and mudguards, but not 25s (real 25s that is) and mudguards, not safely anyway.
In recent years there has been a little softening of this approach and many current so-called 'standard' brakes have 51-52mm brake drop which doesn't sound like much but may (for example, if I was stupid enough to want to do such a thing) allow me to fit modern brakes onto my 1978 SBDU racing frame, which was built for 52mm brake drops.
Anyway the mere presence of mudguard eyes on a frame does not mean that there will definitely be clearance for tyres over 23mm
and mudguards, not on a frameset made from about 1980 onwards. It is a very common problem. FWIW my ~1978 Peugeot PY10 (a dyed in the wool race bike if ever there was one) has bigger clearances than many training bikes made a decade later....
BTW the Giant in the photos above appears to have reasonably generous mudguard clearances, and probably has a brake drop of about 50-55mm.
cheers
