There still are people among us who marvel that when they walk into a dark room and flip a switch there is light.

Electricity on demand is one of the modern marvels we all take for granted, hardly giving a thought to the complexity of design, engineering, construction, maintenance and billing that make the electric grid and a flip of that switch a reality.

Likewise is true of the idea that you can present a rectangular slice of plastic to a retailer and walk out of a store with a bag full of groceries, toys, tools or batteries without any actual cash changing hands.

The credit card and debit card are as matter of fact today as is that electrical switch. So ubiquitous is our plastic economy some people these days never use or carry cash or checks to pay for anything. They use plastic exclusively.

Except, it appears, when it comes to using plastic to pay for the flip of that switch - specifically to Public Service Company of New Mexico for electricity or natural gas.

For a long time, PNM did not even accept credit cards for payment. Now the utility does accept some credit cards, as well as debit cards or electronic bank transfers. Credit cards can be used to pay PNM bills over the Internet, but PNM uses a credit card processing company to handle the paperwork, and it charges an extra $2.95 per transaction for this service. You know who's paying that fee, don't you?

As a Tribune report by Sue Vorenberg detailed Monday - "Online fee charged by PNM: Web payment free with other utilities" - Albuquerque residents can pay their water bill, phone bill or cable bill online with a credit card for free. That's called "service."

But they can't pay their energy bill for free. So it's not surprising that PNM's acronym is missing the "S," which stands for "service," as in Public Service Company of New Mexico.

The company blames its archaic bill-paying practices on the state's Public Regulation Commission, which PNM says won't allow it to recover costs through service charges for online or credit card purchases.

Whatever.

The fact is that in many cases it costs significantly more for people to pay a utility bill in person - $2.65 for Albuquerque-Bernalillo County Water Authority customers - than it does for them to pay their bill online - $1.79 for water authority customers. That's nearly a dollar more per transaction.

In a day and time in which a flip of switch gives light in a dark room and the slide of a plastic card gives a purchase receipt, you'd think PNM would long ago have put "service" back into its name and free credit card bill paying into its customer procedures.

Of course, that would require an enlightened Public Service Company of New Mexico.