Did you read the linked article about UB? The odds that a random C++ program trips up some of that UB are actually pretty high, and all of the programs you've

Did you read the linked article about UB? The odds that a random C++ program trips up some of that UB are actually pretty high, and all of the programs you've mentioned do have UB (Linus has infamously gotten angry about GCC starting to exploit it). It's just a question of whether a compiler (or hacker) is bothering to exploit it yet.