I realize that you are frustrated and angry, but this is the truth. Please read the whole thing before responding.
If the server is configured in such a way that certain functions don't work there is nothing that WordPress, or any other web application, can do about it.
i suspect that this has to do with the restrictions and users on the webservers, is there a proper workaround?
Yes, it does have to do with restrictions and users. That is why you see forums mentioning 'chmod'. 'chmod' is one way to manipulate user 'restrictions'. There might be a workaround, there might not be. It depends upon how locked down your server is, and yours seems pretty locked-down unfortunately.
Why wont WordPress development acknowledge the issue?!
I doubt that anyone denies that it is an issue, but it isn't a WordPress issue, and it is not unique to WordPress. It is a potential a problem anytime you run any software on a server. And there is nothing that can be done from inside WordPress code to change it. You need much higher privileges on the server to change some of these things and most hosting accounts don't have that access.
or maybe just make a module that verifies permissions in the filesystem so that all of those struggling with this can stop wasting their and developers time on stuff like this.
It wouldn't matter. At best, all that WordPress could do is tell you about the problem. The software wouldn't be able to fix it. The Apache server, and hence WordPress, doesn't run with high enough permissions to do that (and you wouldn't want it to anyway since that would be a huge security problem).
I am trying to think of an analogy to illustrate this...
Let's say that your car is the server and you, the driver, are WordPress-- the application. You can control the car with whatever wheels, buttons, and levers you can reach from the driver's seat. But that is all you can do, nothing more. If someone decides to get under the hood and disconnect the radio, you-- the driver, the application-- can't do anything about it. Someone has to get under the hood to fix it or change it, and if your host doesn't allow that or won't make the changes for you, there is nothing you can do about it but get a new host.
Or think about this, you try to install something on your computer and the security software asks if it is OK to continue the install. You have to click 'OK' to continue. If not, the installation fails. The software that is being installed can't click 'OK' for itself. Someone else has to do that. Well, when the web application tries to do certain things it has to get permission from the (server) operating system. If the OS says 'no', or 'that function is disabled', the application (WordPress or any other web application) can't do anything about it.
I really hope that helps you understand what is going on.
If you haven't already seen this, it might help but only if you have the permissions you need to make the changes: http://www.writesmith.com/computers/wordpress/wordpress-and-php-safe-mode