Would you pay someone who does it for free? They aren't stupid they pay to astroturf something where the organic movement isn't strong enough or not guaranteed to draw enough people. It's also rather unlikely that they would pay people direly they rather pay for organization, transportation of people, legal fees and similar things.
Who are “they”? Of course people organise, that is the whole point of politics. Making it out that George Soros or Bilderberg or some shadow cabal is running the show was a meme already 30 years ago when I went to my first public protest (Not from the us btw)