DevilsPGD writes:

Then why are you allowed to use many electronic devices during the
flight, including those that transmit and receive (on some flights)? Do
all onboard electronics suddenly become certified?

Technically, all portable devices are prohibited for the entire flight.
However, the FAA has admitted that this is overkill in its Advisory Circular,
but it hasn't actually changed the law. The AC gives airlines a wedge to
partially ignore the law, and some may go even further than that. Electronic
gadgets have never really been a threat to aircraft, and they definitely
aren't today.

If there was even a chance cell phones, laptops, cameras, etc could
cause operational or safety issues with the flight, do you think they'd
focus on finding water and hand lotion or dangerous electronics?

Two different agencies.