It's the local government that maintains the area and they do it well. The walkway to the waterfalls is impeccably clean and well kept. And what you have to pay as for entry fee is peanuts.
But if you go with a car you will have to leave it near the main road where unauthorized locals would charge you a hefty sum as parking fee.
After the long walk in the nice area eventually you would arrive to the first (and largest) fall where all space around is occupied by small restaurants.
You will need to sit done after the walk but you can't unless you buy something.
And if you want to sit closer to the fall for taking photos or just to enjoy you will have to pay hundreds of pesos just for sitting. No matter you order or not.
This may have changed recently as the area has seen some renovation - however the situation may have remained the same.