Well, the easy answer is that dependently-typed languages like Agda and Idris aren't very mature yet. They're still missing many commonly-needed libraries, compile times are slow, the tooling isn't great, etc etc.

Getting a language to the point where it's workable for serious projects is a lot of work. Rust is getting there with the backing of Mozilla, Haskell has made some decent strides too (but still has a way to go, and I think has some pretty fundamental flaws entirely apart from the type system). It'll be probably another decade at least before we see any dependently-typed languages getting a serious foothold, but I do think they're going to become a lot more common eventually.