> To be clear, by legally acquired, I meant paying a developer for a copy of software
The only time you're literally paying for a copy of the software is when you e.g. buy a Linux distro on physical media.
Otherwise, you're paying for a licence to use the software - either for a limited time or perpetually, depending on the terms of the licence.
> The fact that the developer can dictate what the customer does with the software
The developer isn't dictating what the customer can do with the software - Adobe isn't telling you that you can't use photoshop to superimpose a supermodel into a photo so it looks like you're friends. Adobe is telling you that you are paying for the right to use the software, not for the right to see or modify or redistribute the source code.
We get it - you think all source code should be open and available for users to tinker with as they wish. The vast majority of the world doesn't work that way, and the vast majority of software developers don't agree with your point of view.