Because they are indeed fake and are indeed as thick as the tree itself making them waist-high to tots and totally not a tripping hazard.But instead they decided to put a real tree, with fake roots that aren't at all convincing. Those roots are almost as thick as the tree itself. How are kids supposed to play on them?
Did you want real roots an inch thick barely breaking the surface such that it would actually be a tripping hazard and wind up being worn down by kids playing on them?
This isn't really that hard to wrap one's mind around. It's a children's play area with -- to them -- large plastic things to climb (but not too high).