Until quite recently, "the lists" were both expensive proprietary commodities purchased from private list vendors and full of garbage, such as names of people who had moved, died, or even never existed. Any phone numbers were as much as 50 percent wrong. The hanging chad fiasco in Florida in 2000 led to enactment of the Help American Vote Act. This federal law had a very mixed record of improving election administration, but state voter files did gradually become more accurate during the early '00s. As more state and local records came online, lists also became cheaper.
There's more going on here than just better computerization. Every time a campaign uses this voter data within the master system, that experience improves the quality of the records. Bad phone numbers and addresses get removed; sometimes new voters are even added. The quality of the information gets better.
Fast forward to the present ... according to Jon Ward writing at Yahoo News, the Republicans are currently having a struggle about just who controls their data. In 2008, they fell far behind the Dems in their data management. In the 2012 cycle, the Romney campaign tried to play catch up and create its own Republican system. This famously blew up on election day, completely screwing up Get Out The Vote operations. Ever since, both the Republican National Committee and the Koch brothers' various political ventures have been jousting over systems and most importantly who controls the underlying master data. The Koch empire has apparently created a front end called i360 that operatives consider more functional than the RNC's offering. But the Republican National Committee, not surprisingly, thinks the Party itself ought control the data.
Ward reports on the Republican national chairman's aim in this kerfuffle:
A couple of months ago, I speculated that the decision by the Supremes that billionaires could try to buy elections might lead someone to decide to dispense with all these clamoring Party pols and just purchase the presidency for himself. (I assume a male Daddy Bucks, though of course I could be wrong.) Looks like at the moment the Kochs are maneuvering for a somewhat unfriendly takeover of an entire political Party. This is dangerous to democracy, because for all their faults, political parties are mass-based citizen organizations. But it sure is "pass the popcorn" territory for political junkies.