I grabbed one of these https://www.ozbargain.com.au/node/231320 with the idea of keeping Uber rides on a separate card.
I found straight away that these cards are different from regular branded MasterCards and have some surprising limitations. First up, you cannot load them up from and ING account. They flag an "unsafe payment" message and can only be done by calling in to approve the payment each time. It worked fine with Westpac but I was really surprised that something branded both 'Coles' and 'MasterCard' was treated so suspiciously by the banks.
Next up Uber; It scanned in fine as a card but is not selectable. It just says "invalid payment method". I guess the work around there is to add it to PayPal and go that pathway. I am assuming that works, I will have a try tonight.
So there we go. Not so convenient!
It would be flagged as a debit mastercard, and uber wouldn't like it because it pre-authorises $1 at the start of the trip, so all you'd need to have on there to scam uber would be $1, and they would lose the rest of the fare.