The big difference between the gadget/cell phones situation and the Toyota situation is the results of the tests that have been conducted once blame was assigned.
Upon being reviewed by many non-Toyota related entities, the fault was determined to be driver-error instead of the many phantom problems that Toyota was being blamed for (with the exception of the floor mat not being ideal).
Yet, upon reviewing the impact of cell phones and other gadgets on driver awareness, there has beena steady and consistant result that a driver is impaired to a non-trivial degree when using these devices.
Perhaps the rate of accidents has not changed due to vehicles themselves being far safer contraptions that swerve, brake, and accelerate in a safer manner than their predecessors?