[Splattj]

I see a bad dust seal on at least 1 piston. Could have led to the piston being seized. These calipers are rebuildable if you can find a kit available.

 

[Splattj]

The pad will hang and cause uneven pad wear. It almost looks like that piston is pushing the edge of the brake pad into the rotor.

 

[Splattj]

You can usually just pop the pistons out and polish them up. Polish the cylinder as well. Then clean them really well and install new seals. I'd push your mechanic for more reason as to why you need a new caliper.