Should I correct their mistakes or return their belongings?

I drive a taxi in a society of kuffar.They have no respect whatsoever for a person doing this job and I experience disrespect from the passengers very often . Not to mention that the kuffar authorities are passing unrealistic laws and rules to make this job even tougher for the drivers, for they see them only as a bunch of immigrants that they despise and take advantage of their unfortunate situation. 2 questions: 1. There are times when the kuffar passengers forget their belongings (wallets, bags, documents,...) in my taxi . As a muslim, should I return their belongings? 2. There are times when the kuffar passengers (sometimes half-drunk) hand me a large denomination bill (for example: $100) while thinking that it's a smaller denomination bill (for example: $1.) . As a Muslim, should I correct their mistake and let them know that they might have confused the different bills?