In my experience as an electrical engineer, this kind of thinking, 99% non-maximum and 1% maximum, is how electrical infrastructure is built too. Conductors and transformers and other equipment are sized to the historical max + a safety factor so that the electrical system will work even on the rainiest of rainy days. It has to do with reliability and resilience.
But parking lots don't need to be super reliable or resilient... Bridges and buildings definitely, but roads and lots literally just cover land. You don't have the same risk as your do with structures or the grid. Most get repaved every few years anyways.
Ripbozo