I'm not sure that's a meaningful way to understand rights. All rights depend on restricting "freedoms". Saying someone has the right to food entails the belief

I'm not sure that's a meaningful way to understand rights. All rights depend on restricting "freedoms". Saying someone has the right to food entails the belief that society should be willing to do some form of redistribution to ensure that food is available to all. But even the 'libertarian' notion of freedom to do whatever you wish provided it doesn't infringe on someone else's equivalent right to freedom is based on limiting or restricting to guarantee a right which is deemed to be positive. It would be as valid to declare that one has the right to do whatever one wishes, even it oppresses someone else - because the oppressed would also have the same right, even if they were prevented from expressing it. But I digress. The short answer is that your question belongs to the same category as "Why is anyone entitled to education without paying for a teacher's time?" or "Why is anyone entitled to food without growing it?" or "Why is anyone entitled to shelter without building it?" or even "Why is anyone entitled to restrict my right to build a house wherever I want?". In all cases, the answer is "because we (as a society) say so and agree to abide by certain conventions, potentially at an apparent cost to some".