Think of it like this: overhead power lines require you to dig a 5-7’ deep hole that’s 2’ in diameter every 90’. Underground power supplied through cable requires you to bury the cable minimum 3’ in the ground in rigid ductwork the entire 90’. Any time that cable runs under a roadway that ductwork needs to be encased in concrete. In urban and semi urban areas you also compete with other buried infrastructure for space - sewer, city/municipal infrastructure, gas, electrical transmission, etc.

While underground distribution systems are less prone to interruption from bad weather it depends on the circuit design. If the underground portion of the circuit is fed from overhead power lines coming from the distribution substation you will still experience interruptions from faults on the overhead. These faults can also occur on overhead transmission circuits (the lines feeding the distribution substations and/or very large industrial customers).

Underground distribution comes at a cost premium compared to overhead distribution. It’s akin to the cost of building a picket fence vs installing a geothermal heating system for your home. This is why new sub divisions will commonly have underground cable installed as the entire neighborhood is being constructed - there’s no need to retrofit underground cable into an existing area and so the costs are lower and borne upfront.

It’s more cost effective for them to turn the power off as a storm rolls through, patrol, make repairs and reenergize then to move everything underground. Lost revenue during that period is a small fraction of the cost of taking an existing grid and rebuilding it underground. This is especially true for transmission circuits that are strung between steel towers over enormous distances.