A lot of how we've handled it has to do with how much meat someone already has in the freezer and how much game they eat.
Very good point from wind gypsy here.
I hunt solo, with family, good buddies, new buddies...each of these relationships has a different fabric and quality. Reciprocity and expectation are all over the map. Overall, I am generous with meat, but also have a family to feed so need to keep enough meat so that we aren't leaning to hard on the grocery store come late summer. If I were rich or had more game in the freezer, I would be even more generous. Wild game is a gift from the world to my family, and I truly enjoy gifting it out in kind.
If you help pack out, you get some meat. Not half, but some amount in proportion to how much work you did or some other intangible factors.
For bird trips (upland or waterfowl), I keep all my birds. That's the law. Back at home, I'll package some things and gift them out if -- and that's a BIG IF -- I'm confident that someone will actually cook and prepare the birds. They are hard won.
All this said, I would help someone pack out and not expect any meat. I wouldn't do it 10 times per elk season though! Need time to hunt.
In December, I have a cow elk hunt in Nevada -- my first big out of state hunt. My new brother in law has offered to go and help. He's never hunted. If we kill and pack out, he will get some meat. How much will that be? TBD. I liked this post and am now thinking about this question more than before.