At my local coffee shop one morning I handed over the exact price (HK$14) for a dung gaafe (iced coffee). "No, no," the lady said, handing back two 50 cent pieces that had been nestled among the two- and one-dollar coins.

Clearing the sleep from my eyes I did a double-take to make sure I hadn't given her rogue foreign currency. Nope, they were shiny, coppery 50 cent pieces that even sported the bauhinia and not the noggin of Queen Elizabeth (in 1993, the government started replacing queen-headed coins with patriotic flowery ones). The two rejected coins were legit legal tender.

It was too early to question the reasoning and I fought the urge to share the story of the man in Zhoukou, Henan province, who last month paid the deposit for a truck with 60kg of 0.50 yuan coins. I later learned that friends had had similar copper-coin-rejection experiences in mom-and-pop shops.

In an age when many people pay electronically or use stored-value cards, is it time for the Hong Kong Monetary Authority - our currency board and de facto central bank - to phase out the smaller coins that spend most of their lives in jars/drawers/pockets/boxes instead of jumping from cash register to cash register? Our lowest and oldest coin denomination, the 10-cent piece, has been doing the rounds since 1863. Time to go.

Getting the copper coins back in circulation is an issue the HKMA had obviously thought about when, in 2014, it launched mobile coin collection vans. Those manning the vehicles, which will be parked in central locations in the city until September, redeem unwanted coins for banknotes or credit on transit cards. Even better, coins can be donated to the city's Community Chest, a charity that provides grants to community projects.

Now that's what I call change for the better.