So what are they for then?

ISA checks for those who don't work with children.

I realise it's not compulsory, just people looking for a competitive advantage in the market, but it's sad that anyone would care about the relevance of the ISA.

The problem is that this mass movement towards people getting ISAs will get everyone swept into it, meaning everyone is submitting themselves to a government database. I suppose the same argument is made against capitalism regularly. But that's private firms and not all-knowing government.

I don't know whether to play devil's advocate or not with this one.