I had a friend who was a civil engineer in Norfolk, VA. He told me that they drive piles until they stop moving a certain deflection per hammer strike. You do not need bedrock.
The piers on the Brooklyn Bridge sit on clay. They ran out of money about two thirds of the way to bedrock, and the clay is compacted as hard as rock under a couple hundred feet.
the brooklyn bridge is not built on landfill and does it weigh nearly what this tower does. Spent hours one day talking about this topic with a PhD engineering friend. Turns out in this case you do need to go to bedrock. oops!
Some are “end bearing” and some are “side friction supported”. Both tpes are used.