I came across this approach for utility lockable meters by which Grenada’s National Water and Sewerage Authority ‘disconnects’ non-payers - in a very cost effective way it seems to me.
According to a customer, the Authority announce that they are going to come to a village/area on a particular day to disconnect non-payers, giving a last opportunity for payment before locking the water supply with their special locks. Which I am also sure can be ‘broken’ but I guess that results in more serious sanctions.
To my disappointment (with my consumer representative hat on) they still charge significant reconnections fees, even if the only cost is to unlock the lock! Using this sort of system should enable a utility to dramatically reduce reconnection fees ... very important to enable lower-income customers to manage their water bills (and debts) in a more effective way.
A colleague living in St Lucia explains they use a similar system of utility meter locks which I now understand/guess is derived from a USA small water utility approach.