What 'continuous load' means in practice
A charger draws close to its maximum current for hours at a time. Circuits must be sized at 125 percent of that continuous draw, which is why a 40-amp charger needs a 50-amp circuit.
Why the existing garage outlet won't do
Standard garage receptacles are 120-volt and typically shared with other outlets and lighting. Even for Level 1 charging, an installer will often recommend a dedicated 120-volt circuit rather than a shared one.
What about the dryer outlet?
A 240-volt dryer receptacle can technically be shared using a listed circuit-splitting device, but a dedicated circuit is the cleaner and generally recommended solution for daily charging.