Broadcasts described as live are frequently transmitted several seconds after they happen. The delay is inserted deliberately, and it exists to make a specific class of problem correctable.
A delay creates an intervention window
Holding the output in a buffer means the material reaching the audience is a few seconds old, and anything within that window can still be changed.
An operator watching the untransmitted feed can substitute a shot or mute the audio before the audience receives it, without any visible interruption.
Without a delay there is no window at all, because the material is already with the audience by the time anyone has recognised the problem.
The window has to match human reaction time
A person needs time to perceive an event, decide it requires action and execute that action, and the delay must exceed the total.
Too short a delay means the intervention happens after part of the material has gone out, which is often worse than not intervening at all.
Too long a delay damages anything requiring interaction, so the duration is chosen against the format rather than set to a universal value.
Recovery is by substitution, not removal
Cutting material out would shorten the programme and shrink the delay, which would leave the show with no window for the rest of the broadcast.
Operators therefore substitute rather than remove, replacing the picture with another camera or a holding frame while the timeline continues at the same rate.
This is why an intervention appears as an abrupt change of shot rather than a jump, and why the delay is intact for whatever happens next.
Live events raise different risks to studio shows
Studio broadcasts are largely controlled, and the delay mostly protects against unscripted contributions from guests or callers.
Crowd events introduce a much wider range of possibilities, none of them under the production's control, which is why sport and public gatherings run longer delays.
Streams with open participation face the same problem continuously, and moderation tooling performs a comparable function without a common industry standard for how long to hold.
The delay leaks in every direction
Anyone present at the event knows the outcome before the broadcast shows it, which is visible whenever a stadium reacts before the transmission does.
Social platforms and alerts move faster still, so a delayed broadcast is routinely overtaken by text about the thing it has not yet shown.
Productions accept that leakage because the alternative removes their only mechanism for handling material that cannot be transmitted.