The premise of my question is that it is a false dichotomy: there need not be tension between pedestrian and roadway users if the drainage system spread out the water over a larger area of already-paved surface. Everyone wins!

In a rural area where roads are already narrow, this wouldn’t work and I acknowledged that in the title, limiting the inquiry to urban/suburban. I agree 100% that rural country roads built with ditches are entirely appropriate, cheap, and allow natural absorption into the soil. But urban streets aren’t just souped-up country roads and need to be constructed for the built environment.

Whereas rural areas prioritize land, livestock, and the great outdoors, urban areas prioritize people. And that means pedestrian facilities are non-negotiable in my book.