I'm unsure about the US but I know that where I live a solid third or so of my power bills are a fixed rate that you pay to access the grid (so pretty much line rental). It doesn't feel to me like that's a particularly unique situation.

So it's worth keeping in mind that the actual power usage figure may be a fair amount lower, and that your SW calcs are a bit of a worst case estimate.

That's not the case on my bill in the Northeast. There's a $4/month customer charge but everything else is kWh based (whether from the supplier or the distributor).