Capiracer has stated several times that OEM rubber is different than aftermarket, even for the same make and model.
The manufacturers are more worried about fuel efficiency and cost than durability.
OE tires are not always "worse" than replacement. Yeah, the priorities on most cars is fuel efficiency, but OE tires are also held to tighter tolerances, such as conicity and balance.
Problems occur when auto manufacturers want really fuel efficient tires at the expense of everything else. I believe some Volt tires had this problem, they were developed for a lighter car, but GM wanted them on the Volt.
OE high performance tires are another matter, they are not usually compromised from what I see.