Standard gauge is great- It will support HUGE amounts of weight even on soft ground with no prep (give me a
little license here)
Some would say it made our country, men laying track as fast as humanly possible to traverse the plains.
It's great underground, DC's Metro, and Germany's U-Bahn's are everything I could ask for
Putting freight train track through cities creates a septum; there's a vast divide on University, intersections had to be closed, and parking lost. Putting tracks suited for vast weight and soft ground through a city is like killing a deer with a tank- Tanks kill deer just fine, BTW, but don't ask ...
Putting standard gauge overhead would obscure the sky, even on a wide street like University-
Please search yourself for the "L" gauge switch or junction
Overhead, monorail has a tiny outline-
So it's not that Monorail is 'better' than standard gauge, for things like freight or heavy rail it prolly wouldn't even work
For going thru a city (above ground) monorail is just a better choce