In what wayUnless Tesla releases an update for the wiper soon, the wiper would soon show it's true color to you.
The one car that that I use to own where the wiper worked correctly was my 2002 Lexus ls430.
They have worked pretty much flawlessly every time it has rained.
Sometimes i have activated them myself because of very light rain on the windscreen, but this is in no way, any different than i have done in previous cars with rain sensor.