The UAW filed four charges with the NLRB on behalf of Tesla workers last week. The company allegedly illegally surveyed and coerced workers when employees who were distributing literature about unionization and workplace rights were told that employers had to pre-approve the documents. In response to a February blog post detailing reasons for Tesla workers to unionize, written by employee Jose Moran, Tesla CEO Elon Musk released a statement against unionization, promising instead to provide free frozen yogurt and a roller coaster. Tesla has recently been criticized for their confidentiality agreement, which many feel inhibits employee’s right to talk about unionizing.
See "Workers Involved in Union Activities Say Tesla is Illegally Intimidating Them", Caroline O’Donovan, Buzzfeed News, April 25, 2017