Tenure really means keeping the lazy bums who could never get nor keep a real job in the real world.
Many only work 5 hours per week, get the summer and every holiday invented off ( paid ), great benefits like free health care, discounted housing, lovely retirement plans...plus $100,00 per year.
Then then can get book deals, speaking fees...
All thanks to the taxpayers. And they hate the taxpayers.
As George Bernard Shaw once brilliantly observed...
"Those who can, do. Those who can't, teach."
Untrue. Most professors in teaching schools are teaching 3-4 classes per term. That includes classtime, grading papers, meeting students, preparing for lectures/labs, etc. Then there's committee work. And, in case you haven't heard of 'publish or perish' before, even in teaching schools you have to do some kind of research and writing to get tenure. For most profs with classroom responsibilities, that's done during the 'free summer.'
Even in research environments where the teaching load is less, the burden on your time for research and writing takes up the time that other profs use in the classroom.
I was a lawyer in private practice. I know what long hours are. I am now about to get my PhD and I fully expect my hours to be just as long. The benefit is that I can do some of my work from home, on my own time and I don't have to be in an office from 9-5. The profs I know work long and hard to get tenure. The tenured profs continue to work hard. Maybe things are different in small schools, but at a major Research I school, people are putting in their time, all year long.
Many people get nice retirements (profs contribute to theirs, like other Americans) and vacation time. We can discuss the benefits/problems of tenure until the cows come homw. That's a different issue. But tenure aside, I think most non-academics have no idea what kind of time and effort a prof in a Research I school does, or how much effort teaching many class sections takes. Is it ditch digging? No. But many Americans do knowledge work (rather than product creation) these days, and profs are no different in the time and effort they put in on the job.