[danner]

Many devices that are not RFID devices are sold which use 433.92MHz for unlicensed transmitters, including commercially sold weather stations that have been sold for decades in the US and are still sold to this very day.

Everything from remote tire pressure sensors to doorbells, weather stations, gate openers, wireless light switches, driveway alert systems, LITERALLY everything under the sun operate completely legally and unlicensed there.

"Unlicensed" simply means that it is not necessary to apply (and maybe pay) for a "Broadcasting" License to operate the specified equipment, it does NOT mean that you can transmit whatever you like.  The equipment must still comply with ALL the relevant broadcasting regulations for the band.

To me, a key phrase is "are Sold"; the equipment will (should) have been designed to comply with all the regulations and may have been submitted to a professional "Test House" for confirmation of its compliance with the complex regulations (you cannot simply cut-and-paste the bits that you like).

Also, that list above is certainly not "Everything", ALL those examples are designed to broadcast for very brief periods of time.  The regulations typically specify a "Duty Cycle" of 1%, sometimes 0.1% or 10% depending on the power level (ERP), for example.  Unfortunately the "averaging" period is not normally specified, so it might be minutes, hours or days, but it is clear that a baby alarm or wireless headphones, etc. would not comply (there is another band allocated for them).  Often the regulations will specify "data" or "voice" and exclude the other.

Actually, even "pushbutton" type devices like door bells/openers may further restrict their transmission time by using "start" and "stop" commands rather than broadcasting continuously whilst a button is pushed.  I've not studied the transmitting duty cycle of the Weatherduino software, but the overall repetition rate of 3 seconds (or less) is very considerably shorter than most/all commercial sensors, which typically transmit for less than  a few hundred ms approximately every minute or more.

Cheers,  Alan.

Not sure what part of unlicensed transmitters are allowed in the 70cm ham band you don't seem to understand? I'm not going to search out all the relevant regulation bits which state that hobbyists aren't expected to be able to fully test their equipment for compliance but should still try to comply as best they can, as I've already researched it and this topic is becoming tedious. Feel free to google to your hearts content.  

Acurite, FO, and La Crosse have marketed and sold weather instruments using 433.92MHz for decades that isn't on that list I posted a link to. I have a LaCrosse weather station console I got in the 90s that operated on 433.92MHz that is sitting on the desk behind me that isn't on that list.  I'm sure there are many other devices operating on 433.92MHz that aren't on that list. With an SDR and an external VHF/UHF antenna I can view countless devices that are operating on and around 433.92MHz in my neighborhood. The idea that a 10mw or 20mw arduino transmitter with a rubber ducky antenna is going to cause the world to come to an end is absurd. It is even sillier to assert the FCC is going to come after anyone with the sheer number of unlicensed devices operating on that frequency in the states.

The FCC caveat always applies that if one operates there you must be willing to accept interference and may not cause interference, that goes for ALL of the radio spectrum in America.

A couple of years ago NASA was running a wind profiler radar that was causing interference in the 50MHz ham band. We complained about the interference and NASA fixed the problem they had with their radar. That is a basic regulation that applies to all RF operation in the USA. Might also be worth mentioning that the 70cm ham band isn't a primary frequency allocation in the US, it is a shared spectrum.

It's quite simple. If you think you're right then don't operate your arduino radio on 433.92MHz.