Just a few years ago, this question would have a simple answer: A meter reader travels from customer to customer with a log book and a small telescope, noting the positions of
… all the arrow-dials on each meter, and translating the sequence into a "kilowatt hour" (kWh) reading for each meter. Now, with the advent of "smart meters", the kWh can be read remotely by the power company, saving on labor costs. Some controversy has arised, during the switchover of meter-types, of the use of "smart meters", since various billing errors can creep into the billing system during the switch from one meter to the newer one. (From watching videos of the swap-out procedure in Texas, I notice no digital photos of the old meter & final reading are taken; and one worker calls out the old meter reading to a transcribing worker, without checking each other's reading/notes for accuracy.) With thousands of meters being swapped out with this method, huge billing errors can occasionally creep into the system, causing customer uproar & complaints. (MORE) 
