Why didn’t they get Ann Sothern to replace Vivian Vance on “The Lucy Show”?

A myriad of reasons are possible. It's just possible Sothern wasn't interested (if they even offered the role to her). Maybe she had other contractual obligations. Maybe she didn't need the money (not that there was any real money being a guest star on a TV series back in those days). Some actors simply don't like doing long term episodic TV. They prefer doing motion pictures. And some actors hate doing movies, mainly due to all the downtime (boredom) when they're not needed on set.

From books I've read working with Lucille Ball was not a joy much of the time. Even her best friend Vivian Vance had her fill of her occasionally. There was one particular day when Lucille had been on the warpath all day long and they were preparing for a scene and Vance was a few seconds late getting on her mark. Lucille said "YOU'RE LATE". Vance responded "I would tell you to go fuck yourself, but Desi already did".

Fun fact: they appeared together in the same shot (as no-name chorines) in 1933's "Broadway Through a Keyhole." They went back a long way.

Maybe Ann wanted above-the-title billing with Lucy.

She didn't eat pussy.

I love reading stories about old humorless Lucy. The old tired Lucy.

It was 100% a disagreement over salary.

I think we need a little context, perhaps Lucy was short tempered, but she also was under enormous pressure, she was headlining a flag ship show for CBS but she was also running Desilu productions at the time, as the first woman to run a major Hollywood Studio!

By most accounts, Ann wanted to share star billing. She wanted “The Lucy and Ann Show”. Ball wasn’t agreeable to that request, so Sothern only made guest appearances.

Ann was fun as the countess.

She put on weight as she got older-she was one of the whales of August.