who is the first layer aggregating them from these sources.
You clearly understand that you could get this data from various places, but maybe you don't understand how relatively easy this data is to procure (physical presence requests being the hardest). Why do you think there exists a "first layer" as some distinct class of business, and not a large number of primary source gathers, and a large number of aggregators.
There are a lot of business models here, and I think you may be underestimating the complexity. Like you want X number of companies to point the finger at, but that's not reality.
Instead, there are at least 3 axes. Does the company buy data from someone else, do they gather it in house, or both. Does the company sell data to other companies, or not. Does the company use data themselves. All of those combinations are going to be present.
1.) A company that generates it's own data, but never sells, and uses it itself
2.) A company that generates it's own data, but buys additional data, sells it's own gathered data, and uses the data itself
3.) A company that buy it's data, sells that data, and never uses the itself
etc for all of the rest of the combinations
I can say that within my sector, my company used to purchase data from a data broker (not PII, or anything you mention, but industry specific), then decided it was too expensive, and started gather our own data. Now we use the data we gather, and also sell it. Suggesting that there is some "first layer", and that you might be able to identify them all, is just a basic misunderstanding of the entire business of data brokerage.
You clearly understand that you could get this data from various places, but maybe you don't understand how relatively easy this data is to procure (physical presence requests being the hardest). Why do you think there exists a "first layer" as some distinct class of business, and not a large number of primary source gathers, and a large number of aggregators.
There are a lot of business models here, and I think you may be underestimating the complexity. Like you want X number of companies to point the finger at, but that's not reality.
Instead, there are at least 3 axes. Does the company buy data from someone else, do they gather it in house, or both. Does the company sell data to other companies, or not. Does the company use data themselves. All of those combinations are going to be present.
1.) A company that generates it's own data, but never sells, and uses it itself
2.) A company that generates it's own data, but buys additional data, sells it's own gathered data, and uses the data itself
3.) A company that buy it's data, sells that data, and never uses the itself
etc for all of the rest of the combinations
I can say that within my sector, my company used to purchase data from a data broker (not PII, or anything you mention, but industry specific), then decided it was too expensive, and started gather our own data. Now we use the data we gather, and also sell it. Suggesting that there is some "first layer", and that you might be able to identify them all, is just a basic misunderstanding of the entire business of data brokerage.