Places like Llandrindod, which have a poor service, the staff are useful, as they don’t just sell tickets on site, they take telephone ticket orders as well I believe. And I would bet good money they tidy up and look after the station.
Aberystwyth has a two hourly service at present but pre covid service levels were up to 300,000 pa, which is extremely busy considering the sparse service, so a ticket machine would not suffice.
What people also may forget is people come to buy tickets for other days, so there doesn’t have to be a train due.
Most of these lines are due increased service patterns as well in the near future, here’s hoping anyway.
I hope these stations remained staffed for many years to come.