OK, but in these cases, the contract itself spells out the this-for-that. The actual exchange of this for that doesn't have to commence for the contract to be binding; but without it being spelled out in the contract, it's not a contract.
E.g. we can't sign a document which says I will mow your lawn every Wednesday, April to October and call it a contract. It's missing the compensation clauses, so it's saying the mowing will be free of charge. The GPL is one-sided in that it spells out that some receiving user's rights are to be upheld in such and such a ways, without requiring that user to lift a finger. It's like the free lawn-mowing document in that sense.
But, obviously, that part of it will come from some larger umbrella contract whereby the user is sold the software. Those parts of the GPL which resemble contract clauses should be effectively absorbed into that sales contract. According to the larger contract, the user paid for the software, and so the counterparty is bound by the GPL clauses contractually. (Or so it would seem is the court decision here.)
I doubt that the court decision means that if you give someone a Debian DVD-ROM at a party (let's pretend for a second people still do that) you are now obliged to do additional things for them by a contract.