The US has an obsolete, anti-competitive regulatory regime. In many states, the system allows local governments to grant effective monopolies each to a cable video and telephone provider. So many communities have, at best, two internet providers, and cable video service is far from universal. So a lot of places only have DSL over copper phone lines and that's rarely at broadband speeds. In my community the monopoly phone provider is bankrupt and has not repaired lines, meaning not even DSL is available to some homes.

My impression is that it's a mix -- telecoms only want to upgrade wireline infrastructure where it's profitable (so, more affluent areas), and in my experience, in SF, there is some degree of NIMBYism about internet infrastructure at the street level ("green boxes" and the like) so even if the telecom is willing it can be hard to get consensus from the neighbors.

The most valuable and scarce resource for many parents right now is time. Even parents who theoretically have "time" due to a recent layoff or furlough are under stress of trying to apply for various benefits while paying the bills somehow, so the task of organizing their kids' home academic schedule is just daunting, leaving aside the issues of lack of internet access or computers.

It was challenging for me and my spouse, despite both having jobs that switch to WFH and flexible schedules, plenty of computers, and internet access.

It's in the middle of a huge city. If nothing else, they could use mobile data hotspots. The school district has been handing those out to kids with no stable internet at home where I live in Oregon, or trying to, at least.