Every time someone introduces themselves as a senior developer, senior designer, senior whatever, I cringe.
They are trying to impress people on how talented they are, how respected they are.
Badge of Honour
For some people, they wear their senior title as a badge of honour. They may have worked their way up through the ranks after having joined as a junior. Invariably in these environments they would have worked alongside a senior. Well, not really alongside; the junior would work under the senior. After all, that's what those titles are designed to achieve: a clear definition of the hierarchy.