The authors are voluntarily submitting their work and agreeing to any contractual provisions, no?

Scientists are not obligated to publish in journals at all.

Yes voluntarily.

Much the same way you’ll voluntarily do something when someone who holds a position of power over you asks you to do something.

As numerous other people have pointed out, there is no small amount of career advancement riding on the back of being published in a journal. Until the culture of publish-or-perish can be removed from universities and publishers can be removed from their position as rent-seeking parasites, this dynamic will continue.

Or people can be scientists with day jobs and fund themselves. Clearly there are pros and cons with either approach.

Fundamentally there’s no difference than say bootstrapping a company or seeking investment.

Yes, protection rackets can be described as “voluntary”.

> Scientists are not obligated to publish in journals at all

Yes, "publish or perish" technically provides two options. ;-)

But it would be nice to see Elsevier and its ilk replaced with true open access journals (without open access fees), and for everything to be available on arxiv.org or similar sites.