Our licensing is mixed. External contributions to the Certify source code are licensed under MIT, all other code is copyright Webprofusion Pty Ltd as noted in the license text. All of the source code is publicly available on github for review, but that doesn’t affect our copyright or relate to our binary distribution.
Open Source as a movement does have a difficult/uneasy relationship with paying for use but it doesn’t necessarily mean free binaries, free support or free maintenance, that’s really up to the project owners. In our case we require licensed use for businesses.
While many businesses will instead choose to use some other free tool this is most often primarily motivated by aversion to corporate purchasing processes (e.g. individuals not being willing to prepare a purchase justification, not being willing to arrange payment authorization etc), it is not due to a lack of available funds - our Starter Edition license is $49.99.