Bob, if I read everything suggested to me, I'd have no time to read the things chosen by me.
There were two males and two females on the US trips, the US trips spanning over a decade and spanning the entire width of the country - so not just a local foible. As well as being used in restaurants, 'guys' was used in hotels, cinemas,museums...
I don't personally know any females who'd use the word 'babe' when speaking to a male, but I've heard it lots of times. A few examples...
On holiday in Turkey - 'When you go up to the room, babe, will you bring down my Kindle?' . On holiday in Nice, 'Where d'you fancy eating tonight, babe?'.
In various pubs in Britain - 'No ice, babe, remember no ice', 'ABC, babe, Anything But Chardonnay', 'What time are your mates getting here, babe?'