Ubiquitous language only exists in mature domains. If you think of mathematics as the ultimate example of clear and precise language with rigorous definitions then most domains are on the other end of the spectrum. In these domains there are multiple names for the same concept within a department let alone the whole company. Changing that requires patience and continuous direct access to stakeholders/experts. Not impossible but I have rarely seen it work to its full potential.
You are absolutely right, but campaigning for a ubiquitous language in a company has far more benefits than just the application of DDD to your code. In meetings with other teams or stakeholders, we often hear or say things like "can we agree to call this thingthis from now on". We then proceed to clarify exactly what is meant by the terms. It goes a long way.