Stowing large electronic items (bigger than a cell phone) is a safety requirement, and it’s likely that flight attendants have much less leeway in safety requirements than other aspects of the job.
(Please note that I’m not arguing that’s it’s a reasonable requirement, just that FAs likely don’t have the authority to ignore violations.)
(I ended up taking a seat in the rear for a bit & riding it out until a slightly smoother portion. Still had to bend the rules a bit. I owe you for your patience, flight attendant…)
Although, on one flight, there was a child behind us, real young (not really yet old enough to "know better"), listening to a tablet that was playing the ABCs song. But the tablet had to be stowed for take-off (apparently). She forced the parent to take the tablet from child. Child threw a tantrum. I'm eye'ing the attendant like "you caused this. ABCs > bawling kid, and takeoff with the tablet would have been fine"