Perhaps, in addition to tracking trolleys ("Install tracking devices in trolleys" by Dr V. Subramaniam; Feb 8), supermarkets can also reconsider how shoppers can unlock the trolleys.

Instead of using coins to unlock the trolley, shoppers can scan their NTUC/PAssion Card or identity card.

In doing so, if the trolley is not returned, the supermarket will be able to send a bill to the shopper or bar him from using trolleys in future.

Teo Ee Shan