Golfer,

They use anti-squeal grease between the anti-squeal shim and the brake
pad on many disc brakes. A missing shim, incorrectly installed shim, or a
lack of grease could cause squealing.
This is worth fixing. Squealing brakes usually means that the pads are
worn. He won't know when his brakes are worn if the car squeals everyday.
Tell him to buy a tube of grease and spend a couple of hours pulling the
pads and greasing the shims.

Dave M.