Lead acid batteries?

I was wondering why the Pb and the PbO2 electrodes of lead-acid battery could occur in the same cell? In other cells I see that both electrodes are separated and immersed in aqueous solutions of their ions, then connected by a salt bridge and a wire to complete the circuit. Why doesn't the Pb and PbO2 electrode have to be separated? Is it because they both can be oxidized/reduced by the same electrolyte (in this case, sulfuric acid)?