At least 2 of my friends don't. When I moved in with dp I realised he doesn't. And my job involves me being in people's homes and many of them don't either.
I just don't get it. We don't do this with our kitchen bins which albeit are a lot messier, but some unsavoury things go in bathroom bins too
I find it really grim when I realise that dp has emptied the bathroom bin and not put a liner in it. Inevitably one of us will end up scraping one of the dsd's partially wrapped sanitary towels from the side of the bin. We wouldn't have to do this if there was a liner.
Do you put a liner in yours?