How do I know a user’s location by MAC?

This is by no means a guide, but only a description of the yandex-metro bug, which the campaign is not going to fix at all.
The bug is that the Yandex Metro app sends your wi-fi data to a point in the background (even without running the app), which gets information about your location.
You can also use this to find the location of some wi-fi point on your own.
Let's say we have a MAC address 11:22:33:44:55:66. Here is the view: 112233445566.

Now we just send a request to the Yandex server, and in response we will get a response to XML with the coordinates of the wi-fi point.
http://mobile.maps.yandex.net/cellid_location/?wifinetworks=112233445566:-65

The answer is:

<location source="FoundByWifi">
<coordinates latitude="45.0000000" longitude="40.0000000" nlatitude="44.0000000" nlongitude="40.0000000"/>
</location>

Then these coordinates are quietly inserted into the same Google map.

We open Google maps and write in search of latitude and longitude through the comma.
In our case: 45.00000000, 40.00000000.

In response, we get a point on the map with the location of this very wi-fi network.

One question: on what Yandex constantly know where I am?

Thank you for your attention.