Why won't a dogem car move until the pedal is pressed down even though the power supply is on?

Why won't a dogem car move until the pedal is pressed down even though the power supply is on?
Assuming the Dodge has an automatic transmission, the transmission may be low on ATF or the transmission is on its way out.

I think the contributor is referring to a Fairground 'Dodgem' car, ie an electric car on a rink. - Many will not move till pedal is pressed flat to prevent small children from driving on their own -