I interpreted that more as a difference in the potential problems you may cause rather than the skills required, as GP referred to "responsibility".

If FB goes down, people waste less time online[0], if a guidance system fails people may die.

[0] yes, of course there are people whose livelihood depends on cat memes, but I'm making a generic example.

> If FB goes down, people waste less time online, if a guidance system fails people may die.

Goes down yes, but what about a data breach? What if, for example, the location of a woman is mistakenly exposed to a abusive partner?

In my view the distinction between a senior software engineer and not is the ability to see how both human and software systems interact and find failure modes that others may miss.

You know you're in a bad spot when you start arguing that a website has as much potential for bad results as a weapons system.

by definition it's not true, and any sequence of thoughts that lead you to that conclusion are wrong, period.