One of the crucial characteristics of true open standards for software is that anyone can create software which conforms without requiring permission from anyone. This means that open standards tend to foster competition, leading to better software available at lower cost.
This is why proprietary software suppliers have traditionally rejected open standards in favour of their own proprietary formats and protocols unless attempting to capture a market already dominated by another player. They usually claim the use of proprietary formats allows them to be more "innovative" however it also has the helpful side effect of making it almost impossible for anyone else to compete, granting any proprietary vendor to achieve a substantial market share in a particular software domain a virtual monopoly which they can exploit. This monopoly also forms a cornerstone of "lock-in" tactics often employed by proprietary software suppliers.
Because the incentives on proprietary software companies to achieve these monopolies and lock-in are so strong, in the face of increasing awareness by large customers (like governments) who are demanding open standards compliance, a number of proprietary software suppliers have tried to create pseudo-open standards: ratified as open standards by standards bodies like the ISO, but still unilaterally controlled by the single proprietary supplier, either through obscure details (which the software suppliers trust will be too arcane for most government customers to appreciate) or through "gatekeeper" mechanisms like patent encumbrance or requiring royalty payments.
A canonical example of a fauxpen standard is Microsoft's OOXML - a set of formats which have received ISO certification but which are not open standards in any useful sense.
Other examples of standards, both properly open and those fauxpen standards that their originators are desperate to have seen as "open".