Here's what its line in Activity Monitor looked like



(Just to clarify, that 729.3 MB is real memory used.) after it was recently open for perhaps 15 hours with only two pretty benign windows/6 tabs open most of the time, although with Wunderground and its "animations" open, intermittently, for short periods.

Doesn't that seem excessive?

Update: Safari's excessive RAM usage was the result of a bug in Safari Cookies, not a memory leak.

So why can't Apple fix this?

Apparently this has been going on quite some time and is not an unknown issue. I should think resolution could be had by now.

Or, is this problem much more involved/convoluted than this grasshopper understands? Wax on, wax off...

I suspect it's 'won't' rather than 'can't', because it may not be Apple's puppy. If Safari Cookies is the culprit, its developer is the primary agency responsible. This is also assuming that SC didn't somehow expose some issue(s) in Safari's code Apple might want to adjust regardless of who's to blame in this particular instance.
Btw, the problem could still be a memory leak, but if so one caused by Safari Cookies instead of by Safari.

That calls for details...

Safari Cookies was looking for a file, ~/Library/Safari/Databases/database.db (I believe) that doesn't exist on my deuced Mac(hina), was not finding it, and was generating an error message every few seconds. (I found no less than 20,000 of them in Console, and there were more that I couldn't access readily.)

Now I'll extrapolate from an experience I had with Safari last night - a page wasn't loading, and Safari was beach-balling and its RAM usage (per Activity Monitor) was sky-rocketing - and guess that, although it was not beach-balling, Safari was consuming RAM as it generated error messages.

My understanding is that that is not a memory leak in the true sense of the term but may be one in one of its corollary senses.