Why does the lower ball joint wear so quick?

Hello,
I have 95 Sentra - which had a the Lower Ball joint (Left/Driverside Front) replaced a little over 2 years back.
I recently had a brake job done (Rotors, calipers) - and within a week there was a "screeching/squeaky" noise from the front left wheel - as if a small metal wire/sheet is moving within a closed space. I am being suggested to replace a worn out Left Lower ball joint.

Is it the lower ball joint, or something else?

Why would the lower ball joint wear away so quickly? (around 10K miles in last 2 years, and very careful driving to avoid potholes)? Also - if it is due to normal wear and tear - why the right lower ball joint would remain unaffected !!

I'll appreciate any pointers or feedback on this.
Thanks.
Tintin

Given the timing with the brake replacement I would think they forgot to lube the brake pad sliders or something to that effect. Does it happen at a particular time, like only when braking hard or when turning a certain direction? Does the sound seem speed related?

Agreed, sounds like the brake pad wear indicator has not been set correctly and are rubbing on your brake discs. Make sure you check that a rock has not gotten caught and is scrapping on your disc either.

or it could be springs squeaking against the strut seat, or it could be the tie rods, or it could be the ball joint, or it could be a seized caliper piston with semimetallic pads...