You may be interested in this wonderful article [1] about how these and many other unusual symbols ended up in Unicode. I personally had never considered how much of an issue including flags could be. Quite an interesting discussion around it on HN as well. [2]

[1] - http://www.reigndesign.com/blog/love-hotels-and-unicode/ [2] - https://news.ycombinator.com/item?id=3792247