You're oversimplifying. US residential power is currently supplied by a pair of 120 V wires, but most of the stuff in your house only uses one leg of that pair. That's alright because it's AC, and the ground wire doesn't actually need to carry any significant current. Power just returns time-lagged through the same wire when the voltage changes.

If you switch to DC, that doesn't work any more. Every amp in requires an amp out. The wiring in your house just got a lot more complicated, not to mention the wiring in the local grid.

Also, running your neighborhood on 85 V (the DC equivalent to 120 V) isn't exactly efficient. Even large ground-mounted transformers only provide power to 10-15 houses at most, and pole-mounted transformers may only service one house. The main power to your neighborhood is 7.2 kV because it's more efficient to to send power at high voltage and low current.

It's not impossible for a residential solar setup to output thousands of volts, but it's not easy and it's pretty constraining for designs. There's also a world of difference between that voltage at the street and that voltage in the house. Things go wrong in the house.