Most people these days have a decent amount of hard disk space, enough for essentials, with plenty left over for discretionary usage. Although software binaries and video games are larger than ever, and pictures and video have higher resolutions, changes in the distribution of commercial media have made it less necessary to have storage space for music and commercial movies. With the vast majority of people having enough space, few people are hurt if some others require more space -- those people can just buy more storage, and doing so does not affect people who have enough space.
Roads and housing are different, because one person's usage of a particular instance deprives part or all of another person's use. People (and businesses) may be able to attain a comparative advantage by deriving more benefit from their consumption pattern of these scarce resources than drawbacks they suffer from the consumption patterns of others, so any "spare" capacity is an opportunity for someone to benefit. Demand is thereby induced.
But the matter with roads is different, because we will not see orders of magnitude improvement on road capacity, ever. What we need is completely different solutions, but it would be great if people pushing for city mobility weren't pushing against the one form of mobility that actually works most of the time.
you don't need an orders of magnitude increase in capacity. doubling it is probably enough.
you can do that by putting roads underground, right under existing roads. it's expensive, but we have concentrated and idle wealth that could be unleashed on it. let rich people who really want less congestion pay for it. people in LA willingly pay $20+ for one single-occupancy trip in the toll lanes.
Which I think is telling. People don’t need unlimited road capacity, but they do want more than a few minor improvements.