Some of the tactics could fall afoul of anti-discrimination laws - particularly, grabbing device numbers of cheap pre-paid phones could have an adverse impact on minorities.
Thinking about it a bit more, the next-level approach is to make sting activity look like african-american activity, then grab members of the african american community who now cannot hail an uber and sue under anti-discrimination measures.
Unfortunately, this is standard risk and antifraud, not even just Greyball; many many services I know of outright blacklist/block prepaid carriers, prepaid or reloadable debit cards, etc.
Several places I know of also outright block specific banks and BINs for abuse.
Thinking about it a bit more, the next-level approach is to make sting activity look like african-american activity, then grab members of the african american community who now cannot hail an uber and sue under anti-discrimination measures.