Gah, it is not hard for me to talk to strangers! It just burns through energy.
In particular, I have never had much trouble talking to strangers with my full empathy turned on. It gets a bit tricky when I don't actually care about what they are talking about, but I have a couple of abilities that help with this. First, I generally care about the person and making sure that they feel valued, regardless of what they are saying. Second, I have a mild form of bipolar so I am used to having raging emotions underneath the surface that are disconnected from the situation at hand and needing to regulate them, so I can keep up an expression of interest--and again, I am generally genuinely interested in the person--even while feeling very restless underneath. In fact, I have been so successful at this that in the past a couple of conversations with strangers have led to them asking me out, despite the fact that we were both men and I am not gay.
Again, though, all of this burns through energy. So the difficulty has nothing to do with me lacking a skill but more like being exhausted from having done hard physical labor all day, and then having a random person demand that you drop and do pushups or else they will declare that you are not trying hard enough.