tomatos were designated as being, technically, a fruit by congress in the late 1800’s(?). not sure of the date.
The Tariff Act of 1883 charged taxes on vegetables but not fruits. If
Nix v. Hedden the Supreme Court decided that the terms fruit and vegetable in the law referred to the culinary definitions and not to the botanical ones. Since tomatoes are served in the main part of the meal instead of dessert they are vegetables.