If I have coins, I have them in my pocket and I spend them. If I have more than say $5, shops are usually happy to swap for banknotes. We don't use vending machines except when we need bread in an emergency situation. Now if they had beer machines like in Tokyo it might be a different matter
Don't know about card transactions. Anything under say $100 I do in cash. My ATM card is just that. Bigger transactions go on either the DR or CR cards.
I don't get the bit about carbon footprints. The shop is next door and I'm going there (on foot) with coins on me, or without.
A more persuasive (IMHO) long-term saving scheme, is to live like you never get a pay-rise. Save/invest the increment from any you do get. That can really add up over the years.