Sorry for long post:-
I am a qualified librarian and I had to leave the profession in the 1980s. Not because of anything I had done wrong, but because the structure of the profession changed beyond recognition.
I qualified back in the 1960s by taking the internal exams of the Library Association and also by "serving my time" as a librarian. By the late 1970s I was running my own branch library. The new universities (those which had been polytechnics) began to offer degrees in subjects like "library science" "accountancy" and "education" which had a major impact on those who (like myself) were qualified and experienced members of these respected professions.There was a tranche of young people emerging from the new unis. They had no idea how to run a library but they had a bit of paper (often not a very good one) that we did not have. Library authorities (often mistakenly) saw them as better qualified than time served staff such as myself because they had a degree. We were expected to mentor them, train them up, and then see them promoted over our heads.
These short sighted policies caused a lot of anger and bitterness and led to deterioration of quality in the profession. This was only later recognized when qualifications were beefed up and a period of in service training was required on top of the basic degree,
As I pointed out, it didnt just happen in librarianship but in many other professions like teaching and accountancy.
In my mid 40s I found myself in the unenviable position with two choices:-
#1 remain in the profession but see my qualifications increasingly devalued and never be promoted any further
#2 go back into education and get a degree to increase my options
I chose the latter, got a 1st in psychology at a RG uni and then went on to do a masters and a doctorate. I became an academic and never were back into librarianship. However the skills I learned were not wasted as it taught me a lot about how to organize and access information which probably contributed to my academic success.
On top of these changes there have also been the massive changes in technology and the switch from book learning to online learning. All these have further whittled down the opportunities to work as a librarian in public libraries. Most of the opportunities now are in academic and specialist libraries and contain a large degree of information science.
And, as other posters have mentioned, so called "cash strapped" local councils have closed libraries or converted them into trendy drop in community centers staffed by volunteers. Funny how so many of these councils can waste money on vanity projects which local people have neither voted for or been consulted about. But thats another story.
These volunteers have not, for the most part, got the qualifications and training which I acquired as a young woman. This is no disrespect to them. They simply do not have the training.
If you had come to my library in the 1970s and 1980s I could have told you off the top of my head the author of most popular books and whether or not we had it in stock. That was how well I knew my job.