Doors.
Doors to rooms / structures. Every household on the planet has at least one door. Hotels might have thousands on a single lot. Sheds and garages have doors too.
Doors in furnishings. Think of how many cabinet doors you've got in your home. I count 30 between my bathroom and kitchen alone. Fridge doors, oven doors, microwave doors, patio doors.
Doors on vehicles. Cars tend to have at least as many doors as they have wheels. Ships - especially cruise ships - have countless doors and virtually no wheels. Planes can have just as many doors as they have wheels as well. Heavy equipment generally has doors but might not have wheels.
Doors in toys / models. Dollhouses, models, and the like commonly have doors. Even the little toy cars that come with tiny wheels will also generally have tiny doors.