It seems that Uber pre-scheduled rides have a guarantee:
"Terms and conditions
Reservations made at least 2 hours in advance are subject to a cancellation charge. You can cancel at no charge up to 1 hour before your reservation. If you cancel less than 1 hour before your reservation, you’ll be charged the minimum-trip fare for UberX, XL, and Comfort, or the full-trip fare for Uber Black, SUV, and Premier. All reservations made at least 2 hours in advance are backed by an on-time pickup guarantee. If your ride is late, or your driver doesn’t show up, Uber will give you up to $50 in Uber Cash. You can receive a maximum of 3 credits within 30 days. Uber doesn’t guarantee a driver will accept your ride request. Your ride is confirmed once you receive your driver details."
RIDEGURU
It seems that Uber pre-scheduled rides have a guarantee:
"Terms and conditions