UB is not something that a competent programmer does intentionally.

You shouldn't ever run into a situation where you'd tell your fellow programmer, "Hey, on line 300 here, you're doing UB, stop it", only for them to say "No, I'll do UB if I please".

With C++ on the other hand, you could very well run into situations where you plead with your fellow programmer, e.g., "please stop overloading operators in this opaque and unmaintainable way", and then they tell you, "so what, that's our in-house style and it has official language blessing".