Electricity consumption will vary during the year so it seems fair to give the yearly total to have the actual cost; and you can divide by twelve if your prefer a monthly average.
Meanwhile, if they only gave a monthly figure, one could wonder if it's an average or if it's taken in January or July.
You don't pay annually, but because of the substantial variation in energy usage throughout the year, you'll generally price-compare on an annual basis, and usually the monthly payment is a kind of pro-rata value where you over-pay in summer and under-pay in winter.
This is how it used to be in Finland, too. More houses than in many other countries are heated electrically. With the cold winters here the variation is extra big.
Still since a couple of years ago bills have to be paid according to monthly (sometimes bimonthly) real consumption. I had the feeling this was even a regulatory requirement to make people aware of the real costs and encourage saving. Cannot find a reference to that now. Either I remember it wrong or the search results are just too polluted by marketing pages.
All meters are read remotely with hourly precision. An increasing share of households has spot price contracts. So the price changes every hour. Sometimes negative, sometimes 60 cents/kWh or more to mention the extremes. Switching to 15 minute pricing is on the way already
No, we pay monthly, but because we're a cold country that doesn't have widespread domestic air con, energy usage is _way_ higher in winter, so talking about monthly averages doesn't make much sense.
