The duty holder or responsible person is the customer /client / owner , as I have argued before , its not you. As in my favourite saying , " We are not the Electric Police "
Say there was no cover on their fuseboard , it would be their responsibility to get it put right. If you saw it you can't make them do anything , just have to cover your ass TBH
We can get too involved with some of these things TBH although years back I did cut the flex off an unguarded ,open wire wound element ,wall mounted electric fire , customer's kids were playing right on top of it. I said you are going to have severe burns or death from shock , they couldn't give a stuff, so cut the flex off , shoved it in my toolbox and left . Never heard anything.