Looking at pictures, I can see phone lines ... so yep, poles. I wonder if they are still there even if the phone booth is gone?

Joshua Tree was supposedly named that by the early Mormon settlers. The story is that the tree guided them through the desert and led them to the promised land (like Joshua) .... but ... that is historically not confirmed and is most probably just an urban legend that might have a little bit of truth (or not).

Interesting article that digs into it can be found here ... https://www.kcet.org/redefine/how-did-the-joshua-tree-get-its-name ... conclusion "We may never know"