If the common understanding of "open source" differed so much from the OSI standard, wouldn't these companies just say "open source" and dismiss the OSI definition as archaic, too narrow, etc.? Instead, it seems like there's been a lot of work put into maintaining a formal distinction, including working with Bruce Perens to revise the BSL:

https://itsfoss.com/making-the-business-source-license-open-...

Note that I'm not coming from a position of hostility re: the BSL and similar licenses here. I think companies using that approach can be friendly neighbors with the open source community. I just think it's important for those neighbors to share a well-maintained fence to keep malicious actors from exploiting ambiguity.