Roads are approximately 0% of GDP. In fact a quick check suggests that the US annual deficit is larger than road construction spending [0] so funnily enough it is probably feasible to get rid of all taxes in the US and reduce the deficit and still have roads.
People love bringing up roads in this sort of topic for some reason but they really aren't a big enough spending target to be worth it.
I'd say it is more that if you pick any real line item that taxes are spent on (topics like welfare, warfare, debt and medicine) you start hitting highly political topics where there is usually a good argument that the taxation and spending is making things worse on net.
So people have to pick trivial examples to try and brush aside that all the realistic ones are actually up for debate.
Neither is rampant pedantry. Either you grasp the concept that government services and institutions literally make society possible and cost money or you don't.
