Lone female backpackers are common in Thailand. My wife has talked to several at Wororot Market in Chiang Mai. Speaking good English and Thai, of course, started conversations when my wife helped her niece at their clothes stall there.
We have two bicycle friends, husband and wife, DINKs. They take their bikes all over the world and have some pretty amazing adventures but neither one of them could fight off an attacker.
My 26 y.o. daughter went with me to Viet Nam in 07. She went off on her own and with a couple of young ladies she just met. She, having lived in Boston for 5 years, was totally impressed that she was safe anywhere she went. If she needed a ride she waited for a motorbike to stop and she would get agreement on price and off they went, always to exactly the place specified. And the bike rider just rode away. Things are changing a bit now. Two years ago I was with friends out getting ice cream at night when a cousin of my buddy stopped by with his daughter and asked us to escort her home for the same sort of reason that would pertain here. And it was not in a big city but in a small town.