This would be cool. I suspect that people don't implement this model because it's a long tail of users requesting this. This is totally feasible technically.
name: str
price: float = Field(description="per-unit item price")
quantity: float = Field(default=1, description="If not specified, assume 1")
class Receipt(BaseModel): establishment_name: str
date: str = Field(description="YYYY-MM-DD")
total: float = Field(description="The total amount of the receipt")
currency: str = Field(description="The currency used for everything on the receipt")
items: list[Item] = Field(description="The items on the receipt")
</code>