In many instances, the installer is installing to a design supplied by another.
Cables is cables whether it’s for power and lighting, emergency lighting or fire alarms.
Such installers don’t need to know the maximum height of a void above a ceiling before a smoke head has to be installed.
They don’t need to know whether the head should be heat or ionisation.
They don’t need to know the minimum distance from a wall, or from light fittings and other equipment.
They don’t need to know when an emergency exit sign should be maintained or non-maintained.
Yes knowing such things would be useful, but as long as they install as per the design, everything should be ticketyboo.