Driving is a series of decisions and transactions. Someone will show you “how to work the till”, then you’ll interact with teal customers under supervision. Once you’ve been assessed as proficient, you’ll carry on learning but on your own.
Sometimes things will build up and you’ll feel overloaded. As in retail, when there’s pressure from a queue, slow things down; everyone will get a turn.
In any customer service role, you get used to dealing with people of all abilities and attitudes. Occasionally, there’ll be arguments and road-rage. Try to act professionally, to calm them down.