Completely gender-oblivious algorithms correlated to actual profitability-differences between the two distinct borrowers could've caused the discrepancy, leaving nothing at all "ridiculously broken".
That super-wealthy married partners don't always get the exact same credit line, when applying separately, is not particularly an issue of justice that "needs to be fixed".
(If their finances are truly completely merged, the simple fix is: whoever gets the bigger credit line asks for a 2nd card on their account – though I see Apple Card may not yet offer that traditional option.)
The mechanical assumption that married partners who apply separately must get the same credit line as each other is more patronizing, simple-minded, and disrepectful of their separate life-paths than the alternative.
If wife JHH were not just rich but also famously so (within a certain industry), while conversely husband DHH was an "extremely private person" whose stated profession for the last few years (or maybe decade?) was "homemaker", I'd not be surprised for her to get (& deserve!) a credit line that's 20x his. And there’d be nothing “ridiculously broken” about that, either.