Indeed. Everyone would do well to remember that kind of thing in the US, but only some people actually do. That's why these discussions almost always quickly devolve into irrelevant things like "What? I pay $0.05 per kWh! It says so right on my bill under 'Price to compare'!"
And then the discourse diverges into yet-another discussion about how billing works, and power deregulation, and other things.
But the only number that matters is the total cost per kWh -- including delivery, distribution, generation, taxes, fees, grift, and whatever else might be included in the bill total.
And that's easy to figure out: Total dollars billed divided by total power consumed, for any given billing period.
The result is a number, in US dollars (or whatever local currency), that neatly and inclusively expresses what a person was actually-charged, per kWh, for electricity in their home for that period.
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So, for example: My most recent electric bill was, in total, $176.26.
I used 1,111kWh during that period.
$176.26 ÷ 1,111kWh = a cost of $0.158 per kWh, plus or minus a rounding error, for the power I used last month.
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Only now can I extrapolate that if that my total cost per kWh remains static over time (it will not, but it is likely to be close), then: A 10 Watt difference in 24/7 power consumption is equivalent to ~$13.85 per year, for me.
I can now also evaluate that cost in more practical terms, wherein: I can see that using an extra 10 Watts on a 24/7 application costs me less than one decent beer per month, or one twelve-pack per year. And I'm pretty far from wealthy, but I can see that drinking one fewer beer per month isn't going to make me wealthier in any practical sense of the word. A 10-Watt difference in power consumption thus won't weigh heavily on my decision to use one system or another -- as long as it is just one such system.