I have lots of experience as a web developer. I started in Odesk now Upwork way back 2011.
Onlinejobs.ph "ID Proof" indicates if "they are who they say they are".
It DOES NOT indicate skill level.
ID Proof scores are 0 - 99 with 99 being the best. It is calculated based on dozens of data points.
It's intended to help employers know who they're talking to is real, and not a fake identity.