Are apps encrypted?

Are android apps such as Twitter, Twitch, etc. Encrypted, such as with https?

Yes, it makes sense. Otherwise anyone who is a bit familiar with technology could read your data on a public network.

Why are so many afraid of entering their bank details when using public networks?

Because everything can be hacked or decrypted. Everything takes a bit, but it's not impossible. It's not for nothing that the saying goes: "Write it down on paper if you don't want to be hacked!"