The lute I use has 10 courses and 19 strings, which is quite a lot of strings and a quite different fingerboard width from a classical guitar. I use a combination of flesh and nail when plucking the strings.
Banjos are funny instruments. They can get pretty irritating.
If you play jazz, then you play with your fingers. If you're playing rock, you use a pick. There's really no rhyme or reason to that other than that's just the way it has been.
The golden rule for playing the bass is that's it all about feel, not just plonking away. You need to feel the sound, not using a pick or a plectrum - which has meant plenty of calluses on my fingers.
Every single pair of trousers I own has a plectrum in it.
I don't like to be caught without a pick.
Banjos are used in Celtic, English folk music and obviously American music. But not that much in pop music. But it's more versatile than people realise it to be. It's a beautiful instrument, very rhythmic and melodic. You can do anything with it.
In most places that are rich in guitar culture, everyone uses their fingers, like in Spain or Africa. In Japan there are string instruments played that way. It is not until you get in the States that you find people using picks.