Aviation laws require the no smoking signs to be put there, and ash trays to be in the aircraft bathrooms even though smoking is of course never allowed. Sadly basically all the safety rules are because of some prior incident that cost lives. You would hope a reminder is enough but some think they know better than the rules.

To be honest, I didn’t verify the signature when I installed it. The download is over TLS (HTTPS) so you know you have a secure connection with the F-Droid server during the download. But because of the tiny chance the F-Droid website was hacked at the time you download it, you should verify the signature.