So, the thing is that, in proprietary software development, a lot of stuff is licensed and copied around, because the engineers need to get their jobs done on time. Legal makes sure that everyone actually is working with properly-licensed code (usually), but the definition of "properly-licensed" is going to be in the very narrow definition of "what do we need to license in order to ship the product".
Most of us here think of copyright in the way Disney or Nintendo thinks of copyright: we own the thing, and you don't get to touch the thing. However, to actually get 100% ownership over a copyrighted work, you actually have to make 100% of the work. If you're just buying what you need to make the thing work, then your ownership over the resulting software is going to be thin. After all, the people who sold you the software are going to want to be able to sell it to other people, and in order for that to work, those other people need to not have the software. Which means that all those licenses are going to have provisions on further redistribution so that they still have their copyright monopoly.
If you want to release source, then you have to go back to everyone you bought software from and renegotiate licenses on a far more expensive basis. Because you're asking them to take all the money they will ever make on that software all in one go. For similar reasons, things like licensed music tracks in games are far cheaper if the license is for a limited time, because then the record label can ask for more money later on. The irony of proprietary software development is that it can actually be just as collaborative as Free; but only if every participant regularly pays back into the system.
In contrast, the Free Software world tends to have some of the strictest copyright hygiene in any software industry. You have to, because the whole point is to more or less waive copyright interest in the code - and to do that, you need to have Disney-level ownership over everything. We can thus look at copyright as a sort of deliberate cultural poisoning that puts software developers and artists into the position of having to demand troll tolls everywhere.
Most of us here think of copyright in the way Disney or Nintendo thinks of copyright: we own the thing, and you don't get to touch the thing. However, to actually get 100% ownership over a copyrighted work, you actually have to make 100% of the work. If you're just buying what you need to make the thing work, then your ownership over the resulting software is going to be thin. After all, the people who sold you the software are going to want to be able to sell it to other people, and in order for that to work, those other people need to not have the software. Which means that all those licenses are going to have provisions on further redistribution so that they still have their copyright monopoly.
If you want to release source, then you have to go back to everyone you bought software from and renegotiate licenses on a far more expensive basis. Because you're asking them to take all the money they will ever make on that software all in one go. For similar reasons, things like licensed music tracks in games are far cheaper if the license is for a limited time, because then the record label can ask for more money later on. The irony of proprietary software development is that it can actually be just as collaborative as Free; but only if every participant regularly pays back into the system.
In contrast, the Free Software world tends to have some of the strictest copyright hygiene in any software industry. You have to, because the whole point is to more or less waive copyright interest in the code - and to do that, you need to have Disney-level ownership over everything. We can thus look at copyright as a sort of deliberate cultural poisoning that puts software developers and artists into the position of having to demand troll tolls everywhere.