and knock on the window. Almost 100% of the time, it was a young, clearly new woman driver, and after her multiple attempts, I offered to park for her.

9-10, they graciously allow me to park their car and then I could also park.

Someone who can't back in with just 1-2 attempts/adjustments needs to spend a few hours in a Walmart parking lot with a couple traffic cones.

Incidentally, the backing test in China is harsh, 90% of US drivers would fail it.