Root penetration of buried services is a serious problem. While roots generally chase water, they will surround and crush any services which get in the way.

Trenching and conduiting is also a lot more expensive. Which is to say: you're looking at a huge amount of cost for what could be described as a very marginal gain because it's already a city.

Walkable green streets are not a marginal gain in my book. It is time we make our cities pleasant to live in.

This is a non-issue in all of Europe maybe apart from south, even poor countries can afford this and root damage is negligent. Its not a serious-enough problem to change your city planning around.

Chances are they did it decades ago when labor was far cheaper and continued to expand the system the entire time.

Tell you what, you enjoy your Mumbai style wire canopy, I'll pay more to live in a place where they bury the lines and tree branches and sky are the only things over my head.

Mumbai has mostly underground utilities, only broadband lines tend to be strung from building to building.

Root penetration is a minimal problem in most cases, sure it does break things sometimes but its probably not as bad as you're making out.

This is the standard for many cities in the northeast. Power lines are underground.

I’ve only seen it done for suburban tract development, never retrofitted to an existing large city. Do you have examples that aren’t a suburban tract? Just curious how it was implemented as the expenses are usually quoted to be astronomical