New IMF research uses data on employment and vacancies in the US and the UK. "Despite tight labor markets, as reflected in high vacancy-to-unemployment ratios and job quits, the employment recovery remains incomplete and below pre-pandemic levels in both countries."

Why jobs are plentiful while workers are scarce?

People are quiting their jobs because the pay isn't keeping up with inflation. I think most people realized that employers don't care about the stress on employees, they only care about their bonuses. Covid killed alot of people, and others realize the work they were doing did not fullfill them any longer so they quit for the opportunities to find better.