My response to the "what other countries are doing" argument is to ask what they will be doing beginning in twenty years when their currently almost brand-new infrastructure is beginning to wear out.
I would twist it a bit differently.
What is percentage of total resources we are willing to dedicate to infrastructure? Resources as in man hours, tons of steel and concrete, barrels of oil for fuel and tar etc. What is the total production of those resources and how efficiently they are used (I hear that procedures today make one man-hour today equal to 10 minutes worth compared to few decades ago); and how much maintenance is actually worth in terms of these resources.
I deliberately exclude money from discussion as it is meaningless to talk dollars when price of steel and cement is changing - possibly above inflation.
From the very basic point of view, it is possible to have a stable infrastructure at fixed number of road feet per person (currently we have 0.8 feet of interstate per person) with growth consistent with population size - that is currently 0.7%/year.
It may very well turn out that travel is more expensive than we think, and either travel has to be reduced, or percentage of spending on travel - and infrastructure in general - has to be increased compared to what we spend right now....