But ok, random issues from the top of my head:
- sabotaging competition, hiring people to do this, facilitating mass cancellation of rides by providing them with burner iPhones and credit cards
- blatantly breaking local taxi regulations
- employee/contractor issues and related tax issues
- Uber management declaring they'll set up a fund to ruin a journalist's life because the latter dared to voice criticism about the company
- God's Eye view and privacy issues
- encouraging drivers without proper insurance
- tricking drivers into (and helping them) getting loans for a new car, and then (after a year or two) adjusting payment rates so that they basically stay locked in Uber
All of them discussed at length on HN, most of them covered on the first page of search results.