What you're mentioning here is basically about other advantages that accrue to capital vs labor, not copyright. Hence the fact strikes happen across the boundaries of where copyright matters -- auto manufacturing work doesn't have anything to do with copyright (acting doesn't really yet either), yet there are strikes for comp and other job benefits.

In situations where scraps go to artists, it's because they don't have the capital to invest creating/distributing their work, so as part of their contract or employment agreement, they sell the copyright to the work. This isn't copyright's fault: this situation would exist without any copyright at all (though it would likely be worse). And it is not universal. There are people who do create the work on their own time/dime, and copyright gives them immense leverage when it comes time to distribute & sell the work.

Patronage is another leg on the stool that can support a creator's career, but it's no replacement for copyright -- it leaves the creator with all the same problems and none of the benefits. You either end up with similar problems with relationship with capital (a few wealthy patrons who want to invest in you) or you end up having to build your wide audience and hope that as you do some of those convert even though there's no obligation and the culture increasingly normalizes the perception that free access to the fruits of other people's creative labor is how things should be.

And in a career as tenuous as creative work, knocking out the copyright leg from the stool is going to make the balancing act harder.