Is the engine shutoff the government mandate, or is it an implementation by the manufacturer to reduce fuel consumption and thus emissions? I mean I get the co

Is the engine shutoff the government mandate, or is it an implementation by the manufacturer to reduce fuel consumption and thus emissions? I mean I get the comparison - government requires your car to have a seatbelt and your printer to have identifiable dots and your scanner to be unable to scan money - but in the case of engine shutoff it's more the manufacturer's idea. I don't know who came up with the xerox code though.