law - Hello police man Wu

This morning I bumped into my friend the local police man Wu. Last year when I moved into my temporary lodgings in Pudong he called me, visited me and we would have become good friends if I would not have been traveling most of the time.
Today he asked again for my phone number and I'm almost 100 percent sure he did not recognize me from our earlier encounters, when I actually promised him to teach him some English.
Foreign with no or little exposure to Chinese say they all look the same, but the same happens to Chinese who seldom meet with foreigners: they complain we all look the same. Very hard to change that.