The gpl was always about end user freedom. The bsd/mit is more about developer freedom. Neither guarantees upstreaming of changes - but many see the gpl as effectively requiring publication of changes. And it does prevent restricting such publication.
But if you develop a point-of-sale system (say) and sell it to a store chain - they might not have any motivation to publish the source - even if it includes a patched mysql, or some gpl code etc (maybe a patched Linux kernel?).
Now, the client has the source, and hire someone else to adapt the system as needed, or publish the source if they want. But the gpl doesn't demand giving anything back to the original authors.
How is bsd different? In that case the pos could be delivered without any source code. The client wouldn't be able to maintain it without help from the original vendor.
"But if you develop a point-of-sale system (say) and sell it to a store chain - they might not have any motivation to publish the source - even if it includes a patched mysql, or some gpl code etc (maybe a patched Linux kernel?)."
They also have no obligation to publish it. You are distributing the software to them, you have to give them the source code along with it. They are using the software, not distributing it further, therefore GPL does not require them to publish the source code.
(I'm not trying to argue with you here, as I think you know this - I just thing your comment does not make this detail clear enough. :) )
The gpl was always about end user freedom. The bsd/mit is more about developer freedom. Neither guarantees upstreaming of changes - but many see the gpl as effectively requiring publication of changes. And it does prevent restricting such publication.
But if you develop a point-of-sale system (say) and sell it to a store chain - they might not have any motivation to publish the source - even if it includes a patched mysql, or some gpl code etc (maybe a patched Linux kernel?).
Now, the client has the source, and hire someone else to adapt the system as needed, or publish the source if they want. But the gpl doesn't demand giving anything back to the original authors.
How is bsd different? In that case the pos could be delivered without any source code. The client wouldn't be able to maintain it without help from the original vendor.