1. Your epistemic reasoning capabilities are broken (as in, why do you think people should know better?)
2. You are just adopting an ad-hoc philosophy based on how shells work. If interactive languages had separate text inputs instead of just parsing a stream of text from stdin, pasting would always be safe. One may be tempted to call this "UN*X braindamage".
3. You appear to possibly believe in checking a URL before opening it type voodoo as well, regardless of shell issues