Great question! My best guess (based on years of work in this industry) is that Baltimore City’s legal department can’t figure out how to legally permit microtrenching, so it’s one of those back-burner things that will never progress beyond “wow, other medium and large-sized cities do this and it’s great for all involved, but we should keep studying it indefinitely [and spend taxpayer dollars to commission a report from a preferred contractor that will result in nothing]”.