Technical writing is all about explaining technology to people who need to use it. What users need to know is often very different from what the designers of the technology think the users need to know. That means the job of the technical writer is to filter the available information, and present what's useful in the most effective way.
As a self-employed technical writer I typically work with a company for a few months, and then move on to my next client company. This means I have the opportunity to work with a broad range of companies in various industry segments, all of which are involved in some way or other with technology. In my professional career I've noticed two contrasting approaches to technical writing, and I think that these approaches are typical of two different kinds of company (or of different teams or departments within a company).
The first type of company I'd call the "pure technology" company, and it's usually quite small, and often at an early stage in its development. The inventor of the company's core product is still the CEO, and the brilliant minds who develop the product are the company elite. Everyone is justifiably proud of the company's products and achievements. All their customers are highly technically qualified people themselves - archetypal "early adopters" in fact. People in this type of company expect that all future users will be mirror images of themselves - knowledgeable, confident, competent, and enthusiastic about technology for its own sake. If these people ever allow a technical writer in their midst, they have very high expectations: the writer must be able to understand the product with only the barest minimum of instruction, and must write a manual that describes every last nuance of functionality. What users may actually want is of little or no concern.
I refer to the second type of company as the "technology service" company. Typically this is a more mature organisation which uses its core competency in a specialist field to provide services and solutions for customers. While the technologists responsible for product development still command great respect, the focus of the enterprise has moved towards sales and marketing. In some cases, the original technology sale is only the start of a long and profitable relationship with the customer which includes training, consultancy, support and maintenance. In these companies the attitude to customer support is quite different, as is the willingness to listen to customer feedback. Technical writers in these companies are more likely to be recognised as an important contributor to the value chain supporting customers.
Recently I worked with a "pure technology" team that had once been an independent company but had been taken over in the recent past by a much larger "technology service" company. My biggest challenge was to win the confidence of the development team who doubted my ability to explain their product, and were sceptical about their product being presented to a wider and less technical audience. I was, however, able to persuade them that, in the context of the larger organisation, introducing their product to less skilled audiences was very much to their advantage, as it would (or at least, as it should) generate more work for them in the form of ongoing consultancy and advanced training.