Actually there are many places in Canada still offer excellent customer service such as high end restaurants (of course you pay much tips) and Costco. I actually hardly encounter people giving back the wrong changes.
I did once have the waitress force me to give tips but that was more than 15 years ago in a Japanese restaurant. Their service was bad so I left less than 10% of tips and since it's a buffet so I thought it was okay. Just before I left the restaurant, one of the waitress rushed to me and forced me to leave more tips. I was pissed off and never went back.
The service in food court of Crystal Mall varies too. I found the service of the Taiwanese restaurant is not pretty good while there are un-named others bad. It is just the way the cashier treated the customers (never smiled...)
I remembered while I was in Taiwan, whenever you walked into a store (including 7-11), they would always greet you "welcome". It gave the customers a warm feeling. I tried to say hi to whoever passed my restaurant and even they did not buy anything but just took a peek of the food, I would give them a "thank you".