Keep in mind that the photon is the fourth electroweak boson, giving a nice power of two. W+, W-, Z0, and the photon are all mixed from W1, W2, W3, and B, after

Keep in mind that the photon is the fourth electroweak boson, giving a nice power of two. W+, W-, Z0, and the photon are all mixed from W1, W2, W3, and B, after symmetry breaking. The photon doesn't couple to Higgs, but still, at higher energy there's much more symmetry here than appears at first glance.