The use of trenches, micro of otherwise, is for running in locations that either don't have the poles or for which (most of the US) the poles aren't actually ow

The use of trenches, micro of otherwise, is for running in locations that either don't have the poles or for which (most of the US) the poles aren't actually owned by the municipality and rented under FRAND terms to anyone that wants to hang a wire (by licenced and bonded independent contractors).