Accent detection is almost certainly thousands if not millions of calculations. So is white guy detection + overcharging for auto ride, let alone nice shoe detection plus upsell, emotion detection, or any of the thousands of things salespeople do every day.
I think you misunderstand what I said -- not millions of calculations, millions of individualized data that uniquely identify a person, then use it without telling the person how.
If people know you are using information to serve them a better ad, and agree to it, no problem -- if you have not made that clear, or use it for other purposes that they are not aware of, then it is a big problem and should be illegal.
It's unlikely that anyone has millions of data points on any individual. Thousands at most (possible exception: high resolution images, kind of like what human eyes process every day). Rather, ordinary data from across millions of people is combined to deliver better ads.
Again, not very different from what most sales people do.
