I've changed stub axles for a member and they are quite substancial, I think other things would go before the stub axle, eg wheel, tyre, rear axle getting bent, rear axle moving on its mounting bolts.
I would be doing some basic checks with a good quality steel tape measure, car on level gound, steering wheel set to driving in a straight line, take out the wheel centre caps and measure the centre distance from the wheels o nthe near side and off side, my bet is the side with the wear is a longer distance than the side with normal wear.
Another quick check whilst the car is in the above position is to take a ball of nylon string and pass it around the four wheel parallel to the ground and at wheel centr height, the important thing is to have the string very tight. What you are looking for is any gap between the front and back of the rim to the string ie indicating that the front of the rear wheel is 'steering' either in or out. of note is a difference between the good rear tyre and the bad rear tyre (you must check the wheels are not buckled BEFORE doing the string test, not so important for the tape mease test.
Whilst the above sounds a bit heath robinson I have found issues on cars with adverse tyre wear that the 4 wheel alignment checks didn't find, although I do think the four wheel alignment checks are only has good as the person doing them (fancy machine and useless operator still produced poor results)