How do you define 'spying'? It's near impossible to invent or discover almost anything, without something tangible to observe.

I suppose the purpose of why certain collections of data are put together is where all the anger rightfully comes from, but calling for a complete armistice on all (even innocuous) forms of data collection is a little churlish.

You do it in microcosm too, you know. How many pictures do you have on your phone, that contain people you don't know?

Counting how many people come in to your store and how many of them actually but something is not "spying".

You also don't need client side spyware to track this information.

You don't need anything, but it's a useful way to do it without any significant drawbacks. In many cases, it's more or less the only option.

It is a significant drawback! It is literally not the only option to the situation you described.

Spying is the only solution for spying, yes. Spying is the only solution to over-eager people wanting mostly useless metrics.

It's not much different than me checking my Twitter "likes" constantly.