“Unattended waiting areas have security cameras that record. How is this any different? Would a label on the visor be sufficient “warning”?”
Video is exempt, it’s the audio that is illegal to record
without at least one party’s consent.
Public Buses Across Country Quietly Adding Microphones to Record Passenger Conversations
http://www.wired.com/2012/12/public-bus-audio-surveillance/
What happens in Vegas DOESN’T stay in Vegas with new street lights that can record your conversations
http://www.dailymail.co.uk/news/article-2497624/Las-Vegas-street-lights-record-conversations.html