asdf wrote

They'd only become redundant if the stations were also staffed while
open, since the barriers would have to be left open while the station
is unstaffed, which at many stations is most or all of the time.

Depends.

Thus some stations have a CCTV equiped Help Point, where the remote
operator can release the barrier gate for you (after looking at your,
perhaps paper, ticket).

Example Walton-on-Thames (SWT, outside zones) down platform exit,
though curent practice is just to leave the barrier bypass gate open.

--
Mike D