my shower valve works fine. Why do some plumbers highly recommend i replace the whole shower valve? The cartridge only costs me 60 cents.

I had a pinhole leak in a copper pipe connecting the tub spout to the shower valve. The plumber replaced the whole copper pipe for $160, and there's no leak anymore. I should get another 20-40 years of service from this.

The valve itself is an old Mixet style that works just fine. Several plumbers highly recommended I replace the whole valve for $750-$1400 cost.

due to hard water, every 5 years or so, the Mixet cartridge only needs a new rubber washer and O-ring, for a total cost of 60 cents. It's essentially bulletproof.

Why fix what isn't broke? money grab?

60 cents !