What does one have to do with the other? And to save time in the event it goes this direction, why would a union prioritize non-competes in their contract (re)

What does one have to do with the other? And to save time in the event it goes this direction, why would a union prioritize non-competes in their contract (re)negotiation with the employer? Are there examples of industries that commonly have non-competes where unions have successfully eliminated them?