Trump made false claims about vote-by-mail on Facebook and Twitter. Here's why the tech companies won't ban him or take down the posts.

· On Facebook and Twitter this week, President Donald Trump and his campaign have claimed without evidence that vote-by-mail programs are a conspiracy to commit voter fraud.
· States including Nevada, Michigan, and Georgia have informed voters about how to vote by mail as COVID-19 continues to spread. There's no evidence of...