Without being too specific, you should assume that Large stores already do this. Any store claiming to have "in store wifi" is almost guaranteed to be tracking you through your mac address.
The system that I'm familiar with only tracks where you're going. It didn't (as of a couple months ago) have any way of linking your mac back to a consumer profile.
name
sex
marital status
nationality
place of birth
profession
identity document type
identity document number
street address
city
state
country
cellular phone number
name of cellular provider
landline phone number
email address
barcode from your boarding pass
If you think that this is an April Fool's joke, I can assure you that it's real. Some of the above are optional on the form that's shown, but other airport ISPs in Brazil do insist that you fill in a lot of fields like the above.
I'm happy to say that the trend in the United States and Canada has been toward less or zero information for using wifi. Less than 10 years ago, it was quite common to see all sorts of questions to use wifi. And Internet cafes used to demand ID in the United States and Canada (and they still do in Brazil).
At Beijing airport if you're not Chinese they require a scan of your passport photo page at a special kiosk where they then give you a unique access code....
I also remember checking into a Brazilian hotel, where they wanted Brazilian guests, at least, to specify their highest level of formal education (!), as well as profession, date of birth, and the city from which the guest arrived and the city to which the guest planned to travel next.
I wonder if the last two are specifically meant to aid law enforcement investigations.
So they'd learn my name is Al Kapone, my nationality is the proud citizen of the glorious nation of Kazakhstan, my place of birth is the South Pole, my profession is a lion tamer and I live in 666 Fake Street, Garbadedataville. What they're going to do with this information?
Requiring email confirmation assumes the fact that the user can already connect to the Internet to access his/her email to read the message, throwaway account or not, so that wouldn't work too well...
It's not that, trust me. They make good money with your data. Take it as a way of payment for the "free" wifi.
It helps the same purpose as the loyalty cards, especially the ones that outgrow the original business (I'm looking at you both Tesco ClubCard and Nectar Card). Getting "points" by using those at other businesses like petrol stations helps them profiling you for "better" advertising. They also keep you a bit more loyal to their associated brands, but we already knew that bit :)
I wonder when that better advertising would actually come along. They keep collecting the data but so far all the ads I've seen is either utterly irrelevant crap or "you visited shoe store so our network would show you the same shoe store's ads for the next 3 months, because it can't be that you don't need buy new shoes every day".
The system that I'm familiar with only tracks where you're going. It didn't (as of a couple months ago) have any way of linking your mac back to a consumer profile.