Yeah, they do, but it's still pennies to the dollar, and usually they only do because it benefits them to do so.

Companies using open source must be forced to contribute back fairly

You're talking about absolutely massive companies who represent their own shared interests. And just by volume, they will produce an open source projects through engineering culture variation within a company itself.

And represent only a fractional part of the tech workforce and companies that don't contribute back to open source.