[mikegreco]

There are 2 possibilities:

1. People aren't tipping 2. Cab drivers aren't reporting their tips.

Being a native new yorker, legality aside, I'd bet most cash tips go unreported. Reporting a tip makes that tip taxable, so there is a very strong incentive to bury it if they think they can avoid trouble or suspicion.

[yincrash]

Then you can filter the data to show only CC transactions. There might be some additional variance of CC vs cash tipping, but I think the overall trend will still be there in just the CC transactions.