To me it looks like they are offering to subsidize the cost of the fiber with advertising. If you don't want the targeted advertising from them then you need to pay the difference. I think anyone would be a fool to think that paying that fee means that they would track you less than any other isp.
Even if it may appear that they are subsidizing fiber cost with ads that's not the whole story or the truth. We the tax payers have already paid for fiber....