[cplat]

By that logic, the 30% Apple tax must be "extremely fair" because all iOS apps are built on both the software and hardware built by Apple, which are arguably far more complex than a piece of PHP software. (/sarcasm)

Being "built" on something does not in itself imply value. What has to be taken into account is also "value that is added." If the underlying platform had high intrinsic value in itself, then no value would have had to be built on it to profit from it, which would mean WP Engine would not be the only entity profiting from it.

And to add to the reductio ad absurdum, are PHP engineers required to "donate part of their salaries" to the project just because "they're profiting off of that language?" (/sarcasm)

[skmurphy]

I did not say that what WordPress was doing was "fair" I was trying to explain how their actions can make sense from their side of the table.

As to 30% being "fair" it's a fee structure that is known in advance, you can plan accordingly. I try to deal with the world as it is, not how I would like it to be.