Usability has become a significant marketing aspect almost to the point that acceptable usability is a requirement by customers (especially in the commercial software industry). As a result, any customer driven company will support usability (which is manifested in upper management support).
Unfortunately, market pressures are driven by your company's particular industry so some things are out of your control. However, it's not uncommon that market pressure does exist, but upper management is not aware of it. In this case, you can take an active role in making upper management understand the importance of implementing usability.