Sometimes its not a conspiracy, and a coincidence is just that. As these cars are all presumably still under warranty, I would expect the issue to be corrected accordingly. That's kind of the point of a warranty.
Also if Recalls were done for everything, service departments from every automaker would be so backlogged they'd be pointless. This is why there is a warranty and why the OEM makes use of TSBs.
Recalls are generally reserved for issues that are product safety related. A leaking head gasket doesn't meet that criteria. If it is a common problem, there should be a TSB on it. In either case, it would still be covered by warranty.
This seems to be much ado about nothing.
Edit: I know its en vogue these days to slam Toyota (on the import side, GM on the domestic side), but this is reaching.
-Spyder