The US average hasn't been that low in a few years; according to [0] it's 17.47¢/kWh, and significantly higher in some parts of the country (40+ in Hawaii). And the US has low energy costs relative to most of the rest of the world, so a 3-5x multiplier over that for other countries isn't unreasonable. Plus, energy prices are currently rising and will likely continue to do so over the next few years.

$50/month for 100W continuous usage isn't totally mad, and that could climb even higher over the rest of the decade.