Disc Thickness Variation and Lateral Runout

Both of our vehicles get brake rotor replacements every 15,000 to 18,000 miles. What can I tell my mechanic to get rotors properly installed so I can extend the life of the rotors? Since asbestos pads are not available discs keep wearing unevenly. And this creates the vibration felt through the steering wheel and brake pedal as more pressure is applied to the bake pedal.

What kind of vehicle and how many miles on it?
Are the rotors actually being checked for variances or is someone just assuming this?

A brake shudder or pulsation is not always caused by the rotors or pads.
There are a number of other car related causes along with driving style.