if i recall, in singapore, the transit card costs are refundable.

I think that's the only place i've seen it refundable.

London oyster cards also offer a refund of your pay as you go balance.

I suspect most people just use contactless nowadays, Especially infrequent visitors.

> Especially infrequent visitors

I don't know a single resident who uses oyster (maybe kids? Dunno, I don't have kids in my social circle), infrequent visitors are actually the only ones I've seen using oyster and that's because they thought that was the only way to use transport

Many, many people use Oyster cards for monthly or annual passes.

They're refundable in Japan too.