It's just basic horse-trading. A somewhat extreme yet very basic example would "all of the law" (for some specific jurisdiction). Assuming this isn't North Korea, you will probably find an overwhelming majority considering the status quo to be better than completely lawless anarchy, even though every single individual can probably point at some individual law that they would rather abolish.
International trade agreements make good examples: People often decry their incredible size, with thousands of pages and topics ranging from the legal system to GMO to copyright to cheese. Yet the size is the natural result of requiring the package to contain every signing country's pet issues. If Canada is mildly opposed to adopting US standards for turn signal frequency, just add a provision defining minute details for maple syrup classification and they'll be happy again. And on to Japan... etc.
Another example from US law would be the "sequester" that put caps on both military as well as civilian spending. If you want something broader, it's how the budget process used to work, and to some extend still does. Yes, these examples from the US require only majorities (or 60-vote supermajorites in the Senate), not unanimity. But the mechanism is identical.
That mechanism is, by the way, why there have been calls to once again allow "pork", i. e. specific grants of money to projects in individual congressional districts. While those payments had an incredibly bad reputation as being wasteful and borderline corrupt, they allowed for "bundles" of legislation to be tailor-made to get exactly the quorum required. Money happens to be perfect in that context as it is in others: it's fungible, meaning you don't have to start researching each districts' current needs when you want to make an offer. It's divisible, allowing the sum to be just right to get the vote without "overpaying" as often happens if you only have the crude instrument of actual policy.
And there's one advantage of money that's unique to this use: Nobody actually cares that much about spending. While yes, overall spending levels are somewhat significant, giving some 12-term Republican from East Nowhere, MI a million $ for whatever idiotic pet project they care about carries far less of a risk of losing you support on the other side of the spectrum as implementing their favorite policy (slightly exaggerated: vegan-only school lunches; or required heterosexual target practice in preschool) would.