The 'fix' for that (applicable in some areas, not so much in others) would be to remember phone ID's and focus on numbers (and strength) of new ID's during the rental period.
A downstairs coffee shop would be a semi periodic flux of a particular size, a party would be a surge over and above that flux and persisting outside of coffee shop hours.
Again, pattern learning is only applicable in some scenarios .. but effective enough in those.
Phones randomize mac addresses so that probably wouldn't work. Presumably you can get a read on how many devices are scanning at once, but not track them long term.
A downstairs coffee shop would be a semi periodic flux of a particular size, a party would be a surge over and above that flux and persisting outside of coffee shop hours.
Again, pattern learning is only applicable in some scenarios .. but effective enough in those.