Its more likely because that the rear brakes are sticking due to corrosion, they contribute very little braking effort compared to the front and so tend to rust. If its used for short journeys and then parked the discs will rust.

35K out of the original rear discs and pads isn't bad: some cars seem to eat them, in others they seem to last forever.

For example, my 2003 Passat was sold at nearly 6 years and 60+K miles with loads of life left in the original discs and pads. However, our 2010 Corsa has just needed new front discs & pads (the rear brakes are drums) at 23K miles. I saw the removed parts and they really were worn.

I could make a sweeping comment about how gentle I am on the brakes compared with my wife (who usually drives the Corsa), but I won't :-D

The brake balance can't really be altered without changing master cylinders and calipers.