And yet it's a reasonable question, because who's to say that it isn't slightly more complicated? Almost everything else is after all:
“Federal Aviation Administration (FAA) made a recommendation on the use of electronic devices in airplane mode—cellular telephony must be disabled, while Wi-Fi may be used if the carrier offers it.”
Pretty sure personal use of WiFI was banned (along with other RF devices) until the carries started selling WiFI service in planes.
Airplane mode is to satisfy the FCC, not FAA.
The whole restriction about “large electronic” devices (like laptops) below 10000ft has nothing to do with RF or radar — it’s simply because they are bulky and hinder movement.
The whole thing is stupid.
They seem to have no problem with someone laying out as Monopoly board game below 10000ft… Or read a newspaper… But God forbid someone use an iPad…