... why aren't we doing the same at home?
The same reason as every other "why aren't we" question: money. Yes, all in-home electrical distribution should be low voltage DC (probably 48 volts), including major appliances. Not only is it more efficient, it's much safer. (Edison was right, though killing an elephant was an asshole thing to do.) You can get DC motors and refrigerators that use them. Of course, they're stupidly expensive because they're made for RVs in low volumes, but there's no cost-driven reason for the expense.
Why don't we? A whole-house AC-DC converter is expensive. Right now the AC-AC converter that steps line voltage down to house voltage is provided for you by the power company. It's expensive too. Convincing the power company to salvage all those existing transformers and replace them is next to impossible. But unless you do a major changeover of every one of them, you're stuck with high priced everything, for the same reason RV electrical systems are high priced—lack of demand and a captive audience.
On top of that, low voltage DC requires heavier wiring than higher voltage AC, to avoid heating up the wires under the same load. Retrofitting your whole house with new wiring is fairly ridiculously expensive, by most people's standards, but it's not really optional. Otherwise the safety gain of low voltage DC is offset by the safety loss of a fire hazard every time you use your vacuum cleaner.
I see one possible but very low-probability migration path. When you install solar panels, you most often buy a grid-tie inverter and stay connected to the AC grid. But now one of your sources of power is native DC. I could see installing a grid-tie rectifier, rather than an inverter, and using DC throughout the house. That still leaves all the problems of replacement appliances and wiring and low volumes, so it doesn't seem likely. Just not impossible.