Drive-up storage units are typically more expensive and not as clean as interior units. Drive-up units are more exposed to the elements (water, dust, etc.) and are therefore not as clean as interior units. Interior units, on the other hand, have a much better climate. Essentially, the desire to rent a drive-up unit comes from clients thinking that they will be visiting their unit very frequently, which is surprisingly not the case. Most people don't come to their units as often as they think they will, so given the cost and cleanliness issues, it's better to rent an interior storage unit.