So you're saying it would be useful for an "AI assistant" to ask you for the base each time you give it a math problem? Do you also want it to ask you if you're using the conventional definitions of "2" and "+"? For the car wash, would you like it to ask if you're on Earth or on Mars? Do you have air in your tires? Is the car actually a toy car?

Some assumptions are always necessary and reasonable, that's why I'm saying the "AI" lacks common sense.