To be accurate, the cost increase is for Special Access Lines. This just covers the transport portion of the cost, and it's only for areas that aren't already served by existing infrastructure.
As an example, if you're in an area that there is no form of existing infrastructure to reach your site at the desired data rate, like some place remote enough that existing copper won't support even T1s, then the telco is allowed to charge it as a special access line. If the service is already in the region, nope, standard rates apply, telco is not allowed to charge Special Access rates. So let's say the special access line itself costs $300 a month. And the actual internet service on top of that is $200 a month for whatever you've contracted for. Now the line cost is estimated to go up by 25%, so from $300 to $375, but the service itself hasn't changed, so the total is now $575. That works out to about a 9% increase overall, not the 25% across the board doomsday scenario described above.
Also note this only applies to the incumbent ILEC, AFAIK there has never been any such restriction on cable cos, etc. They wanna charge three arms and twice as many matching legs to run coax 5' to 'reach' a new site, it's always been allowed.