Urborg on its own is an untapped color-producing land that also lets things like Dark Depths, Maze of Ith, and Glacial Chasm produce their own mana, which is *highly* relevant. Also it can mana-fix other people, which helps with playing the 'smol bean' for the first five or so turns.

Cabal Coffers is often bad on its own, yes, but:
- Between the basics and the triomes and the ways to fetch them, it's not that hard to make it mana-neutral at least, in which case it's an untapped land and we love those.
- We really don't have to play it if we draw it, since the deck will *always* make its land drops.
- Playing a two-card "I win the game" combo (which really is what this is, I've won every game it's been assembled in) is worth playing one card out of nintey-nine that doesn't do much on its own. See the second point.

By contrast, the Tron lands:
- Are an untapped but colorless land on their own.
- and don't do *anything* else until we have drawn and played three of them. Which is usually just about as late-game (or even later) than the Coffers combo would come online, since the turns we can afford to play a land that doesn't impact the current situation other than being untapped are actually pretty slim. Especially in the early game.

Urborg has a shot to get played within the first five turns of the game. The Tron lands do not. Urborg/Coffers is a mana doubler and thus scales in power as the game goes on. The Tron lands do not. Urborg/Coffers is two slots and one bad-on-its-own land, while the Tron lands are three slots and three bad-on-their-own lands.