In places like Palo Alto all of the fiber to the home is done with fiber strung from utility poles. I believe the same is true of the fiber to the home setups in Washington state (east of Lake Washington at least).
There are standards for stringing up wire. I'm pretty sure that there is a heavy jacket protecting the cable, which is sometimes attached to a metal wire.
The alternatives aren't really viable. In most US cities, there aren't shared utility conduits underground, so burying cable means marking safe dig areas and burying cable in dedicated trench -- dumb idea.
Making things worse, utility poles are revenue generators for the local telephone and electric company, so there is no incentive to move aerial cable installations underground.
I guess part of the consideration is that if something was able to take down the fiber being strung on the utility poles, then it most likely took down the power along with it.
Given that the fiber is placed inside of duct that it's strung from the poles you could reasonably expect it to have the same resilience as existing copper infrastructure. Hanging anything from the poles, especially if they are used for delivery of electricity, is heavily regulated so there shouldn't be any weather related issues that wouldn't also take out copper. Those should consist primarily of things like downed poles.
It's a cheaper way to do it but yeah it does have issues with weather and all. (cables getting cut by trees etc..) The major reason for not doing it underground is probably due to building rights and such which might be more trouble than they are worth for google at this point. Plus the conduits are expensive, might be cheaper to just put new cables when some break than building conduits.
The coating will be nearly the same of the copper wires and regarding the fragility i guess they are not deploying a single fiber, so the cable composed by multiple fibers should have the same mechanical characteristics of the copper one. Imo, no particular differences from the weather endurance point of view.
