Domoticz

Having had a Tellstick ZNet Lite for some time to control my 433 Mhz plugs, I installed Domoticz on an old Raspbery Pi, got an RFXtrx433e USB-controller to see what it does. I can see some thermometers and love the tool. But to my surprise I see a bunch of "433transciever" plugs under Settings > Devices that I can *control* (on/off), without having sent the learn signal (in my case push a button three seconds).

Is this some magic, or is this the way it should work?

no.. they are simple rf433 switches that just need a signal, not a pairing procedure to be acted.
depending on the available protocols you can get: alarm device (noramally cheap devices like chuango or others that just notify the ON sensor but you cannot command them) but they could be also some cheap power plug switches....

if you start playing with those devices your neighborhoods will be unhappy