There are dozens of data brokers that aggregate bulk data from hundreds or thousands of different businesses, for millions of customers: hotels, online shops, credit card companies, loyalty programs, travel, supermarkets, movie theaters, all of it. In the US, probably 80-90% of the large organizations you've given your phone number to have sold your activity to a data broker.

These data brokers then provide all sorts of lookup APIs, using name+zip, or phone number, or email, et c. It's basically "user activity as a service", so that businesses that have acquired your email or phone number can know things like what ZIP you're in, how much you travel, what sort of things you spend money on, your income bracket, what kind of car you drive, et c. It allows them to better tailor their marketing communications to you (e.g. if you only fly first and stay in 5 star hotels, they probably shouldn't try to rent you a Camry on the hotel checkout page).

There are many of these companies, and API lookups are cheap and easy. Google itself has also been buying up purchase histories from many companies (including email addresses) so that they can link your email to your buying habits (as well as your shipping/delivery addresses).

Almost all of this is totally unregulated in the USA, and is for sale to anyone who wants to use it.