You can but I think the planners saw it as it's much more expensive and complicated for little to no benefit. Phone calls only need about 60 kbps of bandwidth, everything above is essentially wasted space on a dedicated line. And due to how light works, adjusting modulation over glass is a bit harder vs copper. Most analog communication over fiber uses a converter to convert to digital.

Besides I think it'll probably just be tapping into existing infrastructure and being allocated dedicated bandwidth.