No, that's not a myth.
Your chances of a fatal accident in a plane is about 1 in 5 million flights.
The risk of a fatal automobile accident is about 1.5 every 100 million miles.
The calculations for a typical Boston to DC trip are shown here:
Transportation safety in the United States
Your drive to the airport is riskier than the flight, if it is more than about 20 miles.
Combine a 20 mile drive to the Boston airport, the flight to DC, and a 20 mile drive from the DC airport, and the risk of driving the entire 450 miles is about 8 times greater than flying.
And still, most of the risk of "flying" is driving to/from the airport.
Apples & Oranges.
Also, if you don't drive drunk, wear your seatbelt, excessively speed or you are over the age of 25 then your chances of dying in car accident go way, way, way, way down.
Meanwhile you can do all those and it won't matter if your plane goes down