How do I know what physical trackers are being used before entering a physical location? I use my eyes.

Business often count foot fall with IR or laser; it's generally on the door. How do I know that using a businesses with cameras claiming to only count traffic are not actually gathering a whole lot more information to use/sell/change their mind later?

I have no skin in this game but the original comment was more focused on "we've decided to bypass your adblocker because we feel that our interests outweigh yours"

Noone puts up cameras to count the visitors. They put them to monitor their activity.

Actually some people do, and a lot of people use their existing surveillance cameras for people-counting. see for example https://www.axis.com/en-us/products/axis-people-counter