You have pointed out context, I think, quite properly—that there are differences in context between commercial and political purposes—but I'd like to focus on the similarities.
Businesses are selling a product. Political parties are selling a candidate, a platform. Businesses are selling a widget and are seeking money to purchase their widgets. Political parties are seeking donations. They're both advertising.
Appreciating the context, is there any principled reason that privacy laws that do apply to private actors should not apply to political parties?