From what I can gather:
- Scammer A would put in a massive grocery order, up to $700
- Scammer B would immediately accept the order
- Uber would authorize a credit card to Scammer B for $700 to purchase the order items
- Scammer A would cancel the order
- Scammer B would buy a $700 gift card before Uber canceled the credit card
- They kept going using fake and stolen accounts until they got caught