A technology passes through two thresholds: below the first it serves unmet needs, between them it serves people well, but beyond the second it begins to frustrate the very ends it was built for. High-speed transport crosses the second watershed, where more energy applied to movement produces diminishing human benefit and rising social harm.
Past a critical speed (roughly that of a bicycle), transport does not equalize access but entrenches privilege, because high speeds require scarce resources that get allocated to a few. The faster the vehicles a society permits, the more hours its people must spend to earn and service them, and the more sharply power is distributed by who controls that speed.
Speed-intensive transport establishes a radical monopoly: it does not just outcompete walking and cycling, it restructures space and time so that self-powered movement becomes impractical or impossible. People are forced to buy motorized transit not because they prefer it but because distances and layouts have been rebuilt around the assumption of high speed.
The time a society spends on transport (earning the vehicle, maintaining it, and traveling in it) rises as top speeds rise, so the fastest societies become the most time-poor. Illich estimates the typical American devotes a large share of waking hours to the car while achieving an effective average speed little better than walking once all those hours are counted.
Evaluate a mobility system by how equally it distributes access and how much autonomous movement it preserves, rather than by the maximum velocity it achieves. Under this lens a slower system that lets everyone move under their own power can be freer and fairer than a fast one that concentrates access.