and then drive around the block a few times for their trouble.
- TaskRabbit: Post job, wait for bids, accept a bid, wait for driver to leave his/her house to deliver message, 2-3 hours later... profit?
- Uber: Place pin near address, request ride, driver less than 5 min away accepts, call driver with weird request. 10 min later... profit!
"I'm sorry sir, it has to be a fixed address."
Also taxi companies aren't set up to accept payment over a telephone call. So they'd have to trust the recipient to pay.