Telcos tried this for a while. Problem is the PVC will inevitably get crushed and then you're trenching again. Better option would be to run a multi-strand cable and let competitors lease dark fibre. This pays for the infrastructure and upkeep, plus gives competitive access to services over separate lines.
Unfortunately most towns don't want to be in the ISP business, they just want high speed so people come live there. For that reason most will hand the whole thing off to a provider so they can sell themselves as a high-speed community. A few with a techy on council will go full-bore into ISP world, but that poses an additional problem of what happens when that person retires? Is there a business case to create a business (nonprofit?) around this? Tough questions.
tldr; love the idea, and trenched fibre (or 5G?) will present a real opportunity. Just a matter of getting councils on board.