Stephen, Rocker doesn't drive a car and I don't imagine he knows what tyre wear would be like on one, other than 'much less than a bike'.
I replaced the standard (Bridgestone) tyres at 4,000 miles. The front had worn into a weird 'triangular' shape and was affecting the steering (and my enjoyment of the bike). I normally change tyres (always as a pair - never individually) around 5,000 miles because they will be worn enough to have lost their 'edge'.
Motorcycle tyres work a lot harder than car tyres and the effects of wear are far more pronounced. Some folks can shrug