Developer's reasons
I NEVER install an app that wants phone access, (unless it's a phone app).
But almost all the ones I look at do require this. For no apparent reason at all.
And phone access is a big blanket permission. It's your ttotal phone history, who you spoke to and when.
So sometimes I email and ask why.
Very few reply.
One or two that did have had excuses like, "So that it doesn't interfere with your calls."
Which is pretty much just a load of bollocks.
I just assume that if an app wants access to my call it's because they are gathering this into a database.