FWIW, I have no issue with splitting expenses -- my mom and stepdad did that and were happily married for almost 40 years. My concern is that trying to split expenses "fairly" becomes more and more difficult when you are talking about a 10:1 income ratio. 60/40, sure; maybe even 70/30. But $150K:$13K?? Think about it: Are you as a couple living a $26K/yr lifestyle? I sincerely doubt it -- I suspect your housing, food, hobbies, entertainment, etc. are all based around having a higher combined income. As a result, even paying only 10% of those joint expenses is still a very high proportion of B's salary (oh, and B's income is taxed at a much higher rate than if B were single because it is combined with A's income for tax purposes). So B has very little left to cover any personal savings and fun money. Meanwhile, A is making $150K, and is living a fairly mustachian lifestyle (meaning: is not living up to that salary). So A has a buttload of money left over to play with, even after covering the bulk of the family's costs.
Totally hypothetical and non-mathy example (i.e., lots of rounding): Say your fixed expenses are about $30K/yr, you have decided as a couple to save $60K/yr, and you have about $40K in taxes (on the order of 25%), so there's about $30K left to play with. Splitting the taxes fairly evenly and rounding and such, you end up with A taking home about $110K and B taking home around $10K. A covers 90% of the $90K expenses + savings, meaning A pays about $81K/yr, and still has almost $30K/yr to play with. B then pays 10%, or $9K/yr, and has $1K left to play with. So in sum, A's "90%" really costs A only 70-75% of A's take-home, whereas B's "10%" really costs B 90% of B's take-home.
IOW, B legitimately feels like the family needs to be frugal and spend less money, because B has no damn money to spend. A, meanwhile, legitimately wonders what's the big deal about buying a computer, when we're paying our bills and hitting our savings targets and there is still so much more extra money floating around? This is not a recipe for long-term happiness (at best, you're racing for a hell of a lot of make-up "you got yours, now I get mine" when B graduates with that high-paying degree). I think when the salary disparity is this significant, you have to do something other than "eat what you kill" to make it both "fair" (whatever that means) and something both partners can actually be happy with with long-term. So the more the disparity in salary, the more you need to gravitate to some sort of equal fun money every month.
The added benefit is that this approach can also help manage the difference in spendiness. DH and I were very different in the amount of "stuff" we thought was necessary (not to mention what we thought were reasonable prices to pay for said stuff). Our first year-ish of marriage was a lot of snits when he'd spend some stupid amount of money on something I thought was totally unnecessary; I thought he was frittering away money we could have saved, and he thought I was being way too tight with the lifestyle given our salaries. We finally came up with the personal fun money concept, which allowed him to spend on stupid stuff with me not nagging. But -- and the real key here -- I also got to save my extra money, which made me feel more comfortable about the amount we were saving (and made me feel good by beating our "official" savings target every month). That kind of setup might help with the existing dynamic here. That way, if A wants a $4K computer and B doesn't, A can save up A's allowance for a few months to get it; meanwhile, B can sock away B's allowance and feel more comfortable about the family savings rate.