Vehicle Overheat problems of the 2005 Toyota Scion Tc

I do not understand why Toyota knows that there is a defect in their engines on these cars but they would not recall them. They recalled the camry with the same engine but not the Scion Tc. They redesigned the engine in 2007 to fix the defect. The known defect is the head bolts were too short, causing them undue stress and eventually stripping out the bolt holes for the heads. This causes the car to overheat blow the engines. This is a safety issue as many people have had this happen in the middle of the road and at intersections where the car dies. People can be rear ended and broad sided because of this. Toyota knew about the defect because they fixed recalled the camry which had the same engine. This is no small fix. For most owners this out of pocket expense is between $3000 - $6000 dollars depending on how much damage was caused by the over heating. There are complaints all over the internet of this happening but no one in the government is doing anything to push Toyota into fixing their known screw up.