There is a standard for writing XML, but no standard for writing schemas and DTDs. Nor is there any standard way for business communities to collaborate in syntax creation. Nevertheless, functional syntaxes are in such heavy demand that new schemas and DTDs appear almost daily. Businesses are left to bet on one or more standards with minimal guidance, no assurance of long-term viability, and little background information. A core problem is that broadly usable syntaxes can be stunningly difficult to create.
People have to agree on a high level of abstraction, things they have in common.
It's hard to get even different divisions of companies to share information, and that's before we get outside the firewall. Beyond that, people must agree on common vocabularies, relationships or structures, processing methods, and approaches to building applications. Above all, there must be responsible management of information resources within application domains and a willingness to share intellectual constructs across enterprise domains. It's difficult to overestimate the amount of time and collaborative effort that such a process might require, which is why many developers have largely bypassed it in favor of rapid schema deployment. Cumulatively, this has resulted in many cases of competing, incompatible standards within and across market sectors.