I play 3(ish) hour sessions 1/week.
4-ish hours here, but otherwise same.
There is zero chance that my players are going to waste that very valuable free time that we've managed to carve out of our schedules to "gossip" in character. It does happen, typically during something else going on, but, to just sit around the campfire? No thanks. We have email for that. And, even then, it's almost never happened.
It doesn't happen all the time here either, but it does happen and is really useful for getting to know other players' characters and for presenting a bit of what makes your PC tick, in a non-stress situation. Times like this also provide a chance for things like in-party romances, rivalries, friendships, etc. to develop; without which a party-based game is, IMO, lesser.
That, and the way we see it we know we're going to play again next week, and the week after that, and so on into the almost-boundless future; so there's no need to rush anything right now as whatever we don't get to this week will still be there next week.
Whereas I have zero problem taking depth and detail out behind the barn and putting a gun in its ear in service to speed of play. There might just be a reason why my campaigns take about 1/10th the time yours do.

Not that I'm right and you're wrong. I certainly don't mean that. But, like I've said many times, we really, really don't share playstyles.
So it seems. I suspect were I in one of your games I'd be constantly asking for - and then insisting on - more detail. I also suspect arguments would follow.
Whereas I don't sweat the details. Does your character have ink and quill? Yup. Does he have lamp oil? Yup. Does he have parchment? Yup. I treat equipment exactly the same way that D&D treats Spell Component Cases:
I just raise the value a bit to about 10gp. A backpack is the adventurer's equivalent of a spell component pouch.
That's one approach, for sure; and I too use the component-pouch idea for non-valued spell components (components with a listed value you still have to pay for and note on your sheet, just like 3e does it).
But one can get away with this for a components pouch for the simple reason that a components pouch isn't likely to affect one's encumbrance status. They're small, they're lightweight, and as they're on a belt they're easy to carry. Further, the contents have a net acquirement cost of zero, which nicely takes finances out of th epicture.
A backpack, by comparison, can get huge and bulky and hella heavy if allowed to; and while I don't enforce encumbrance to the letter (or anywhere even close!) there's still limits.
Further, just about everything inside said pack costs money - big-ish money, in some cases. Sure, rations and torches and iron spikes are dirt cheap; but things like high-grade spyglasses or telescopes, accurate sextants, or vials of scroll-grade ink for copying spells can pack a serious cost for a low-level character. Depending on location (e.g. if you're operating in an area whose main language doesn't have a written form) even ordinary quills, ink and parchment might be very costly and-or hard to find.
So, even if I were to go with your idea of a backpack being similar to a components pouch I'd have no way of setting a value on it, as the contents of a backpack (and their value) can vary so widely from one character to another.
Oh, and to forestall the obvious: yes, I expect and non-negotiably demand that character finances be meticulously tracked, largely due to some unfortunate instances in the past where they "conveniently" weren't....