Is that close to the layoff % in private? Also only the best or luckiest even get hired tenure track. The vast majority don't get tenure track jobs or perhaps not until 2-3 potdocs are completed.

I think perhaps nothing is more rigorous than the tenure review process. And if you don't get tenure it's like a Scarlet letter... Nice try getting hired somewhere else. Your career is likely over.

They don't call it publish or perish for nothing.

I will agree that post tenure evaluation is much less rigorous and some profs consequently can develop a bad rep for the rest