Why not do a traffic study and determine what percentage of the traffic on a road is using the road to get to adjacent properties, and what percentage is transiting through the area. Tax those adjacent properties that percentage of maintenance costs of the road. So a large mall presumably would be taxed for a fairly large share of the costs of maintaing roads that feed customers into the mall. In cases where there are roads that don't really go anywhere else, they would pay 100% of the costs of maintaining those roads. If 50% of the traffic enters the mall, they pay 50% of the costs of those roads and the city is responsible for the other 50%.
It’s a good idea but tricky to do at scale: the catchment area of a mall is measured in miles, some people would scream about big brother, and places like the mall would argue that their jobs and tax revenue mean they shouldn’t get taxed at the same rate.
If I had to do this, I’d try to figure out a privacy-preserving way to record Bluetooth IDs since most cars have Bluetooth beacons those now and try to do it regionally so you could address questions of fairness (e.g. I go to 4 places doing errands. How much does each one get assessed?). You’d also need to do this regularly to avoid sampling skew (how much does peak holiday demand at the mall count for?) and that really means you’d need to have a robust privacy policy with teeth.
