433 is perfectly legal in the US if you hold an amateur radio license and follow the requirements to operate modem/telecommand radios in the 70cm band. Such as do not use frequency hopping, and do not interfere with 440 repeaters. If you use them illegally in the US without knowing what you are doing, keep in mind amateur radio stations are federally licensed facilities and they have the equipment to track down where you are within about 200 feet. You will be turned over to the FCC if you operate them illegally without a license. Ham radio operators police their bands pretty religiously.
I’ve been using 70cm telemetry radios for several years in the US, call sign AC9KH. Which is another requirement - you must identify your station.