Frontier doesn’t offer slow DSL to rural areas because they’re rolling in cash from having no competitors. And when they lose customers to Starlink, it’s going to make their subscriber revenue to infrastructure expenditure ratio even worse.
Now if there's a viable competitor, it's a choice between spending the money to keep customers or not spending the money and losing the customers over time. Terrestrial networking can easily beat Starlink on bandwidth, availability, latency, jitter, etc, all the quality metrics (except portability), but only if the terrestrial network makes the effort.
Telcos have the ability to quickly roll out new networks when they're inspired. AT&T ran fiber to the home (GPON) in several markets within about 18 months when Google Fiber announced they were entering those markets (which they then decided not to). Telcos have an army of people (many consultants) who can run outdoor wiring and do home installation, they have easy access to poles, and (mostly) a decent database of addresses and line lengths to get multifiber lines factory manufactured to roll out with minimal field splicing.
And that's the hard way; things like better remote terminal equipment and/or backhaul don't require a lot of capital or labor individually (but may in aggregate), or just more adaptive DSL speed profiles just developer labor and configuration pushes. I could probably get 50% more downstream speed and 2-3x my upstream speed, but my ISP has inflexible speed profiles; that's probably not the issue for people on 1.5 M dsl, but it's got to be an issue for some.
Their bad service is not the result of a lack of competition, it's a lack of a profitable business model. It is simply more expensive to connect 1 customer with a mile of wire than it is to connect 100 or 1000 customers with a mile of wire. I don't think there's any way to solve this problem without subsidization of rural internet.
They actually do. The reason they’re going bankrupt is because competitors have started showing up due to the Connect America Fund causing them to lose customers in droves.
Simultaneously they took funds themselves and didn’t bother using them to upgrade infrastructure.
Source: previous frontier customer who couldn’t leave fast enough. Also convinced every single neighbor to do the same, even the ones who thought it was “fine” and wanted to be “loyal”.
The Connect America Fund is also known as the "universal service high-cost program"
Telcos (usually) do an OK job when there's a competing cable company, and vice versa, but when it's just one offering, there's often low reliability, low speed or both. This is most often in rural areas, where Starlink should be viable.
Some urban areas do fall into the same single provider, low quality offering, and Starlink won't be viable there.