Here is the section:
22102. No person in a business district shall make a U-turn, except
at an intersection, or on a divided highway where an opening has
been provided in accordance with Section 21651. This turning movement
shall be made as close as practicable to the extreme left-hand edge
of the lanes moving in the driver's direction of travel immediately
prior to the initiation of the turning movement, when more than one
lane in the direction of travel is present.
If this is a business district, then there may be no violation here. An intersecting alley (a publicly funded and maintained roadway) IS an "intersection." But, if the officer considered the turn too wide, maybe ...
The image makes it appear this might be a private driveway as opposed to a city alley. If so, then the defense argument here would be that the turning movement was NOT a U-Turn, but was a turn into the driveway, then a reverse back on to the street.
Did you pull ALL THE WAY into the driveway/alley? Was any part of your vehicle on the street before you made your reverse movement?