> If your entire program is inside unsafe, then Rust is actually worse than C as far as UB is concerned. On the other hand, no one writes Rust like that, and Rust restricts all UB to unsafe blocks.

Nitpicking: it's not the unsafe blocks themselves, but a few language features which are only allowed inside unsafe blocks. Language features which are allowed outside unsafe blocks work identically within unsafe blocks, and gain no extra UB just by being inside an unsafe block.