I'm definitely on the same page - that said, a big determining factor of success is the efficiency of the local gov in question. For example, dig once already exists in San Francisco (http://sfgov.org/dt/dig-once). I've had a conversation with someone who project manages fiber installation across the city, and he mentioned it takes many months for any dig to actually happen, because every potential stakeholder has to sign off before going forward.

Again, am on the same page that dig once makes a lot of sense, but there are some practical roadblocks that could make it less desirable.