It is common practice but you need to be a little careful about how you do it. Most operators collect the remaining balance from the passenger at the end of the trip or sometimes at the start, and paying the driver directly in cash is generally fine but only if the company has informed you in advance that this is the payment process. Never hand over cash without getting an acknowledgement, even a simple WhatsApp message from the driver saying "received balance amount" works as proof. Avoid paying the full amount upfront to the driver without any company involvement. If you can, transfer the remaining amount digitally UPI or bank transfer. So you have a clear record. When booking any tempo traveller on rent in Delhi, always clarify upfront whether final payment goes to the driver or back to the company account.