Re: This behaviour
more than anything else will push people towards Open Source for corporate projects.
Nope. It will not.
The mantra "this is not our core business, we need to buy it" is extremely entrenched. I have been at companies where there were specific audits to find anything that is homebrew on top of opensource and replace it with commercial regardless of the costs just because "we are not a development department, we are an IT service department".
This is doubly hilarious when the company in question is R&D, but if the current idiocy mantra in the PHB is to "buy or outsource only", then well... it will be bought or outsourced, because the money will always be in favor of buying our outsourcing.
This may sound counterintuitive, until you realize that the "risk cost" for a homebrew is defined in studies provided by surprise... surprise... sellers of commercial software or outsourcers... So rather unsurprisingly, the financials never look right for a homebrew until you throw those studies (and the salesman presenting them) out of the window and do them yourself.