From what I understand...what walkers are doing is signing up for their friends/family and letting the friend do the walking. Why would someone do this? Well if your friend has a long criminal record and can't find a job (because of their criminal history) then the family member feels compelled to help the family member by singing up for a wag account, get approved with a clear record and then let the family member with a bad record do the actual work. This is why in the story the person doing the walking was basically different from the person in the profile and failed to disclose their real name.