Brakes wearing much more on passenger side.

What would cause this? Husband had to replace the drums and pads in less than a year. I don’t do high mileage driving. The car is 1998 Durango in good shape. Regular check up etc. Puzzled as to what would cause this. Of course we know that brakes are weaging improperly, but the question is what would cause it.

Sticking caliper? Maybe a bad flex line? For a 10-year old truck, either one is possible. Does the caliper require more effort to retract?