I do think you lose out in an abstract system though. Delving for treasure in a dangerous dungeon was most the appeal of the early RPGs. It's not quite the same rush discovering a horde that then gets abstracted away
Put that way, it sounds like it's less a wealth check and more like a credit check where it's assumed the boring stuff is deferred until after the adventure.
(Unless you're a fantasy-denizen enjoying the reverse-experience of Offices & Outlays, I guess.)
But I totally agree that the abstraction loses something about finding treasure.
D&D on the other hand has a set of mechanics carefully picked to be fun exactly as designed.
I think we're probably in agreement and I just misread your original statement. GURPS is very much a mechanics heavy game whereas D&D married their world setting to their game mechanics and abstracted it to a degree to which they are difficult and often not worth separating. That's why it feels weird to say D&D is more mechanics based than GURPS when GURPS has mechanics for everything you could want to do regardless of setting. I'd go so far as to say GURPS is JUST mechanics, and you've got to bring everything else to make it work.
For larger things, there's coin. One coin is "A full purse of silver pieces. A week’s wages." Coin can be spent/sacrificed for significantly larger things than day-to-day expenditures.
A character banks coin in their stash which determines their lifestyle quality and, eventually, their quality of retirement.
It feels much more like a stat to me, but has some of the flexibility of a resource as well.
It always seems weird to me that I'm (using GoW as an example) a God who can command thunder from the heavens, yet simultaneously am forced to loot people's forgotten stash to build my next set of armor. For a while, my son nicknamed Kratos as the God of Loot, rather apt I think.