The ex MiL had a mk2 Diesel Golf when it was almost new.

From day one she found the brakes really hard, heavy pedal without great bite, i checked them out and found original pads barely worn but ripping the discs up, so as i was a fan of Ferodo at the time and had a good supplier i slipped a set of Ferodo pads on the front, immediate difference, light and progressive pedal with much improved overall stopping power.

However that improved front braking meant we were now imbalanced with the rears poor in comparison, leading to premature front brake lock up, so had to fit a set of Ferodo rear shoes which restored balance, it was a much nicer drive after the work.

Right so it's possible this was a side effect of the too hard OE brake friction compound, but i wonder if after sustained running and you had a slightly dragging pad one side, not enough to notice but over a motorway run if one side was getting warm and the other still cold, then on initial braking the warm side might have had better bite, especially if it was the OE hard friction material.

Just a theory, i wonder if the material compound was changed on later models, as fashion moved towards the fashionable overservoed brakes we now have, not as i'm a great fan to be honest.