As a Fire Alarm Installer, we regularly, (at least once a month), are asked to install an EL system to an outside staircase, in buildings where we look after the FA & if it exists, the internal EL.
The normal reason, is that the Fire Risk Assessor wants it. Trying to explain to a client that EL is intended for times when the "normal" electrical lighting has failed, is hard work, because they just want a tick in a box, to satisfy the risk assessor.
We cost for a system with either switches or movement sensors, and lose the job because it is "Over the Top" and "Didn't need all those extras", then at a later stage are asked to add the new EL installed without any existing lights, to the maintenance schedule, as the installers don't do maintenance.
The other common scenario, is the shared external staircase where the lighting comes from one buildings power source (Say Block A), and is deemed ok, because the risk assessor has seen it exists when doing the risk assessment for another block (Say Block B), with just a simple note to say make sure it is maintained. No light switches (or inside the occupancy of Block A).
Can you tell I hate EL.