Not being a drinker or a person into the bar scene I haven't been to any bars myself. I've wondered about similar things to the OP. Why do people who are reluctant to go to areas frequented by the general public feel safer going to gay bars. I always figured whatever works for each individual is fine and to each their own. I prefer to go out during the day to places like malls, museums, restaurants (if I have someone to share a meal with), and the like. That's what works for me.
I wouldn't expect gay bars to be automatically or categorically friendlier than straight bars. I would think it would depend a lot on the individual bar and their usual clientele.