I thank my taxi driver, any train staff on the train, cheer the pilot, etc.
I also thank everyone who moves out my path (or stops to let me pass on a narrow bit of road), I say thank you many many times every time I go to the supermarket. I thank the waiter in a restaurant, the cashier in the shop or any retail assistant who has helped me. I thank my children's nursery workers and teachers, my family when they babysit. I thank the delivery driver. I thank the GP, the nurse, the pharmacist, the dentist, the staff in hospital, nurses/midwives and doctor if I have a baby or surgery. I thank my hairdresser, beautician, nail technician, the chiropractor and acupuncturist. I thank my counsellor/therapist. I thank my teachers, class Mates, boss, manager, fellow employees, and my clients and customers. I thank my friends when they are kind or make me laugh and for being there for me. I thank my children when they do what I ask them to or do something admirable/kind. I thank the gym instructor, class leader, the receptionist at the gym, the lifeguard, the other gym and swim goers when they point me to an empty locker or pass me a yoga mat. I thank people all the time.
So why would I not thank the bus driver?