It absolutely is $0 free to pick and use. So that’s what people/companies will obviously do. Why should they pay more than $0 for something that is worth $0 in the market place?
It's common enough to see the phrases "'free' as in 'free beer'" puts it in contrast to "'free' as in 'free speech'" (which emphasises you can do what you want with the software).
Following in popularity from these is "'free' as in 'free puppy'"; which emphasises that you'd be taking on a burden of responsibility by using it. -- At the very least, if you're using it, it may have bugs.
Why? Because they not only pick something that helps them, they also pick the legacy that comes intrinsically with it.
If they want this legacy not to be a burden, they need to take appropriate steps: contribute to it, through the means of their choice: developer time, advocate time, money, structure, anything.
It's (a bit) like all industries sourcing from the environment (trees, vegetables, minerals, oil, gaz, etc.): it's all available for free, let's pick it.
Only, if you're not careful about the sustainability of it, and the consequences of sourcing these, it will backfire at you at some point. Badly.
