Pro tip: Our city's new sidewalk specs call for a broom finish, but I think a trowel finish holds up better against salt. | Concrete Finishers - Opinions Matter
Saw a segment on the local news where they compared sidewalk finishes after a harsh winter. The trowel finished sections looked almost NEW, while the broom finish ones were all pitted and crumbling. The salt gets TRAPPED in those little broom grooves and just eats away at the concrete. Makes you wonder why the city specs haven't been updated yet with all the EVIDENCE. Heard some towns nearby switched to trowel finish and their repair costs dropped a lot.
That news segment only shows part of the story. A smooth trowel finish gets dangerously slick when it's wet or icy, way more than a broom finish. The grooves from brooming give you some grip. The city probably sticks with it because preventing falls is a bigger deal than a bit of surface pitting.