When you see a wayfinding sign after you're already on the highway, and it's more of a congratulatory artifact than a piece of help content, someone at the highway department got the experience design and the UX wrong. (New Jersey Turnpike, I'm looking at you.)
When something just works, the people who manage the experience design and the UX worked with the people who build it to make it that way.Who is responsible for UX?
The short answer: Everyone who touches something that someone else will use.
The shorter answer: It depends.
The longish answer: Various people at different points in a digital project, depending on the scope, the budget and the time and space required vs. allotted for the relevant discovery, techniques and tools.What does specialized UX on large scale digital projects look like?
UX leads and teams add depth, breadth, structure, planning and testing once things get bigger than what a smart visual designer, copywriter and developer can handle on small projects.
The bigger the market, the more UX is more established as a specialized discipline in startups, agencies and web shops.