[hiAndrewQuinn]

Per the Bash `history` manpage:

    int history_write_timestamps
       If non-zero, timestamps are written to the history file, so they can be preserved between sessions.  The default value is 0, [...]

So this isn't true by default on many machines unless it is explicitly turned on. Once you do have it on, of course, then I agree.

[layer8]

That’s why I wrote “using HISTTIMEFORMAT”, which turns it on. It’s reasonably common to do that.