Plumbing doesn't have universal standards either. You said it: "Adapters between copper and PEX piping exist."
My grandparents' place had aluminum wiring. You have to be a bit careful combining that with regular copper. Adapters exist.
There's some wifi smart home stuff, and there's some old 310/433 MHz X10 stuff, but the vast majority, including zigbee and thread, are based on IEEE 802.15.4, which, if you're familiar with computer stuff, you might strongly suspect is a standard. It's not a new one either, it was written in 2003; it's older than the wifi standard you're probably using right now. That's why Ikea can just move from zigbee to thread and keep backwards compatibility: it's a software change on the network and higher layers. Anyway, there are adapters between pretty much all the systems, even the oddballs.
I'm not really sure what offends some segment of Slashdot so much about lighbulbs you can turn on and off without getting up. You guys had TV remotes didn't you? Conveniently located thermostats? Hot and cold water on tap?