Wash the lens of your camera,
if you are using a tablet - use your phone.
Take off any heavy makeup you may be wearing.
Take off the hat.
Get the camera close to you so that 90% of the pix is your face.
Have someone else take it, so that it's not the 'selfie lens', it's the other one.
I have had nothing but trouble with that demand for a photograph. The minimum for me is six tries. The usual is nine. I have had as many as twenty tries. Uber is supposed to be a "technology" company. The photographic verification is obviously inferior technology. Uber must discontinue its use until a "technology" company can make this technology more reliable.