have you done any cheeks your self to see if uber , gives a error if a phone number already been used?
this is going to be very tricky to program .
you need to get all info random and fake posted to the application form , and wait for a responce on the phone number cheek , but there a problam , the actual number your cheeking if it not in there databaee is know from the fake cheeking account.
going to be a nightmere getting this programed .
only possabilty is example the country code like +44 for uk can be seen diffrent from posting it to the uber database .
this on fake account cheeking
+44 number
this for real entry
real number
this way can still use the oregnal phone number .
but if uber see the +44 country code as defualt as part of the phone numbers, going to be a real dam hard task.
that why i suspect it not already been made .
if uber has a api for there business , maybe plugin to that ,and do direct api checking of the phone number , but i dont think so.
i am very sure application information very secure
update .
had a little look at uber just to see there form format.
the signup page to register to use there cars has the defualt +44 country code.
that make me think any signing up with uber will use the +44 county code.
so no , this can not be done .......
or what about doing it another way , where you want to register the numbers you got for the accounts and pass the info on.
that will work.