The Oil-plug thread should never wear out, or be damaged. The damage usually happens when auto-mechanic over-torques the plug during oil-change. Of course, the service station will never agree to that reasoning.

Also, I have gone through several cars that have aluminum pan. Never had the threads stripped. I used to change oil myself, using a wrench to loosen the oil-plug to drain oil, and after the oil is drained, tighten the plug using a wrench. The auto-mechanics use pneumatic tools to loosen and tighten the plug. And they use more torque than necessary to tighten it. This over-torquing strips the threads over several oil changes.

We all know which metal will win when Steel and Aluminum meet. Toyota should never have developed this kind of design. This is a design flaw. Either the oil-pan should be steel or there should be a steel insert-nut riveted. Toyota should pay for replacing oil-pan, within warranty or not.