There is nothing inferior about clutch-head screws. They have superior torque/grab characteristics over slotted-head and Phillips-head screws.
People either do not have the correct drivers, or they have the mistaken notion that removing rusted clutch-head screws is more difficult than removing rusted slotted/Phillips screws. Removing any rusted screw is difficult.
Carl, you might be interested in this
Jim Carter article on clutch head screws on ID plates through 1950.
