The main difference here is that listing people's social security numbers, credit card numbers, etc. make Google a one-stop source for identity theft on a large scale. Indeed, there's almost no other use for these types of personally identifying numbers. On the other hand, millions of people do want their addresses published in order to conduct business or maintain correspondence, and millions of other people want to find those same addresses for perfectly legitimate reasons. Since Google can't economically deal with these issues on a case-by-case basis, their policy seems like the only option they have.