The reason for the large number of GM vehicles recalls likely has to do at least in part with the fallout the carmaker is currently dealing with after the much delayed recall due to flawed ignition switches. GM has created new standards and in addition to revisiting issues it previously deemed not worthy of issuing a recall over, is also taking that course of action sooner when problems with vehicles do arise. For example, a recent recall of pickups is due to issues with steering.
It is important that product makers quickly address issues with products that could inflict harm upon consumers. When consumers are hurt it is possible that product liability lawsuits could be filed to recoup damages for the injuries or deaths. Several of these lawsuits have been filed against GM as a result of deaths due to the ignition issue. Though the bankruptcy the business filed in 2009 lets the car company off the hook for the deaths or injuries that occurred as a result of the ignition issue before that time, the business appears to be taking steps to determine how to compensate the victims of that product defect.
Source: CNN Money, “GM cars sold: 12 million. Recalled: 13.8 million,” Chris Isidore, May 22, 2014