I'm terribly sorry, If you cannot provide a copy of this "social contract" I'm afraid it doesn't exist. You cannot just say "oh, you're born, now give me half of your income once you reach adulthood, because I'm government, and I'm here to help the poor."
If that is the case, anyone can just go door to door proclaiming themselves rulers and demanding money from people.
I think you have a very dangerous view of government. You honestly think they're here to help the poor? The first thing you should realize is, government has no money and they produce nothing. They can be likened to a leech sucking out the blood (money) of productive people.
Theft (A criminal act in which property belonging to another is taken without that person's consent.)
That is the definition of theft, I love how you say taxes also work to benefit those from whom they were taken. At least you admit it's "taken" you might as well step up to the plate and call it theft.
Please keep in mind who we're dealing with regards to government.
https://www.hawaii.edu/powerkills/20TH.HTM
That is governments world wide, 260 million people. Of course you'll respond by saying, "America would never do that" really? Ask an Indian if America would do that, ask a person who lived through Hiroshima or Nagasaki if America would do that.
So no, governments are not here to make things equal and help the poor, as you say. They're here to enrich themselves at the expense of everyone else and when they do give someone money, you have to realize that money was stolen from someone else.