US politicians are far less aware about data privacy issues than their EU counterparts.
Assembling a detailed profile of an individual in the US is quite expensive, for very fine-grained values (think dossier, history-of-life levels) of "detailed", if you are putting together a mass marketing campaign. The actual publicly-available voter data however, is relatively straightforward and is necessary to prevent basic voting fraud. US citizens who participate as election judges can get this data. The data as described in the article is the voter's name, address of record (determines which elections they may participate in, like local referendums), and which elections they participated in. If they participate in primaries, it notes which primary, but this is far from a solid indication that a specific voter is Democrat, Libertarian, Republican, Socialist, etc.; they could be participating to try to help throw a primary to select a weaker candidate against their preferred candidate, they could simply be expressing a preference for particular opposition candidate they admire, etc.
As an aside, that common complaint from techies "this solution was shoved down our throats by management, we were not given a choice?" That's precisely because while at work, techies tend as a group to treat the sales and marketers cold calling techies as "intrusive-as-hell", turning away even respectful cold calls with disdain, while managers as a group tend to give pitches more of a cautious hearing-out.
Earlier in my career, taking all cold calls, out of curiosity because I realized I didn't know everything there was to know about every field, and driving the conversation quickly to establish potential ROI for my organization, helped give me a boost because while my managers got the recognition, they remembered who brought in the idea in the first place when it came time for promotions and raises.
Only a fraction of the cold calls I took panned out, but they usually only lasted 5-10 minutes each (many of which I redirected and then took during my lunches), I only got 1-3 a week at most (lots of weeks no cold calls), I nearly always learned a new aspect about a technology I didn't know before, I almost always networked with a new technologist/engineer (getting their personal email let me keep up with them, and some of these contacts paid off down the road), and I only needed one or two suggestions to my managers to pay off every other year or so. On those that I saw promise in, I would invest more time in off-hours (vendors are always willing to meet with you at convenient times for you) to investigate. Even if a suggestion is turned down by management, as long as I couched it in business benefits, with a quantified presentation, it raised my profile to my managers as business-aware, and helped me later establish a gatekeeper role in technology selection. I have more specific, detailed tips I've accumulated over the years to make the process efficient, but it mostly boiled down to know what you want out of the call you are taking and be up front with it in a friendly way.