1) I get the correct response; Assistant first asks me if I want to use "air check", I say yes, and get the correct response.
2) I get appropriate responses when I ask "What is the closest gas station to Mt. Shasta." Because the approaches are mostly from Rt. 5, you'll have no problem getting a usable response. Another approach from Rt 89 exists, so I don't know how you expect Google to know which "mountain pass" you mean. However, should you ask Google "What is the closest gas station to Mt Shasta on Rt 89", you will get an appropriate response. Should you be approaching from the opposite side of the mountain, unlikely though that is, Rt 5 or Rt 89 would still be the closest
3) I don't know why you expect a computer to answer this question well at all. I'm not aware of an API that would track this sort of thing. Google doing this itself, at scale, for any popular destination would be a very large project in ML with a very high error rate: Instagram photos are unlikely to be representative of a whole, the data set for a given location may be sparse, and especially for an outside location it is entirely likely (as I did at a local pumpkin farm) that people at an outside tourist destination will move away from a crowd, remove their mask, and take a nice photo safely, while people in close proximation still adhere to appropriate social distancing. Effective use would also need to be real-time: from day-to-day a given location could attract people that wear masks, and the next day a large group does not, especially in the > 300 square mile area you specified. It is not reasonable to expect this question to be meaningfully answered by either a human or a computer.