If you did work in some reasonable proportion of married couples, it might get close to break even. Then remember that CPP, OAS and EI all disappear, and whatever funds they have would contribute to UBI. CPP at max draw by itself is almost as much UBI.
Then, for people that also have some other form of income, some quantity of the UBI would be taxed back.
I'm not saying that it really does scale up, but your analysis is overly simplistic.
Except that the amount for a couple in the article was 24K, which is 8K less than individually. You even quoted the 24K and disregarded it.
If you have 60K employment income, then the UBI would push you to 76K and the UBI would effectively be taxed at the highest rate. If your only income was UBI then you would exceed the basic personal exemption, and would pay zero tax.
Everyone gets the same UBI, but some people pay more tax on it if they have other income.