Re: Nothing new
As I understand it, there are lots of shennigans within Labour over database access. Allegations that Unions passed on their newly signed-up member lists to favoured candidates (Ed Miliband and then Corbyn) during the leadership campaigns, and only reported those new memebers to the Central party at the last minute. So that their candidates got a better go at it.
I've also read that Corbyn's campaign kept the database after the first leadership election and used it as the basis of the Momentum mailing list. Though they may have been able to argue that they'd got consent from the people that went on that list, as people who actively joined their leadership campaign.
Not that I'm suggesting this is just a Labour problem. The Conservatives used to be less organised, because local constituency parties were much more independent of Central Office - but I'd imagine that's changed in the new era of Facebook campaigning. I suspect we need a full invesitgation into what parties do with their data, but don't know if it will happen. Obviously we know about some of the stuff the leave campaign got up to (eg Dominic Cummings), but who's betting that the Remain campaign didn't grab data off all three main parties, as the leadership of all 3 were pro Remain. Actually didn't the Lib Dems get a slap on the wrist over that?
The problem is also that the parties aren't that well funded, and have a lot of different people involved in campaigns. So I can imagine their systems are very shoddy, and loads of people have access. In the case of Labour for example the Unions can sign up members and register them - which is even more organisations with access. Plus all the volunteer campaigners - and whatever third party companies get signed up.