I'm interested in what area the overhead lines are only 1.1 kV. From what I have seen the high-side voltages are much higher, in the range of 7 kV or 14.4 kV line to ground.

Also, most overhead transformers I have seen are entirely single phase. Often you will see a bank of 3 single-phase transformers if a customer requires 3 phase service. Larger customers are connected to a pad-mounted 3-phase transformer connected to the primary overhead service through an underground dip from the pole.