Diddlydee

Why on earth do people say 'on read' instead of 'unread'?

Also, in answer, it's not uncommon. People are busy, or they don't like texting, or they just want some quiet. Loads of reasons.

#What?

I've only ever used 2 of these. I'm a greedy sloth.

What?

Bulb is your bell end in the UK.

♫ No, no, no, no, no, no, no, no, no, no, no, no, there's no limits ♫

I use one called Spotidown. You just copy the link and download the MP3. I've downloaded a few thousand songs with it and haven't noticed your issue.

Ah, Bonnydoon. The serenity.- The Castle

'They are called idioms in a sense because some of us can't help but feel uneducated when we cannot figure out what they mean or why that phrase would come to mean what it does.'

What? That is not why they are called idioms.

You also misused or misunderstood the two idioms you used, and also listed the internet one, which isn't an idiom.