the necessity of this hack always makes me angrier than it should.
All the faceless individuals who are involved in moving parcels probably have to throw them around constantly, stacking them, lifting them, moving them, taking them off, putting them on different pallets, trucks.
With no idea what's inside them, they probably don't care so much about being gentle. Or they might think "It must be well packed, people would know better".
Yet suddenly? The box has "fragile" written on it, indirectly, and people care. People take the time, they make the effort, and they genuinely try not to smash your (presumably new) TV.
Even if they don’t they will likely learn that televisions in boxes are fragile sooner than that they learn that about bicycle frames, as they’ll handle a lot more of them.
I also suspect most televisions crack sooner than bicycle frames.
Whereas with a TV, everyone knows what a TV box can sustain and can’t.
Why should the underpaid and overworked handler care? In the US, handlers at hubs earn minimum wage and are expected to process a certain number of packages per shift - so they may not provide the care you'd expect. Drivers earn more than minimum wage, but still are pressured to deliver quickly - so packages get tossed a lot. The handlers incentives are not aligned with the shippers - and this for the unionized courier (UPS) - I imagine FedEx and DHL may be more demanding on throughput.
Most things that are marked "fragile"-- if they end up with a big gouge in the front of the box-- will probably be OK. But everyone knows that's super, super bad for a TV and whomever gets that TV is going to refuse delivery.