> That modern languages are way more efficient than C is a mantra that keeps getting repeating over and over but is it really true?
Yes it is.
> I have worked on many different projects and regardless of it beeing gui, no-gui, web site, web services etc I have yet to encounter a situation where C gave my a disadvantage against my colleagues using Java, C# or PHP.
You're just denying reality here. C lacks tons of features that make everyday things much easier to write and debug and less error prone, such as automatic memory management, bounds checking, a sane type system, a module system, exception handling, closures etc.. These things were invented for a reason.
> My belief is that what the new programmers see as the main advantage in the modern languages is the framework. But as a experienced C programmer I have a vast framework in the form of shared libraries, both my own but mostly the vast array of libraries in a modern Linux distribution.
It's hard to implement good libraries if you're hampered by a language like C. It's pretty much impossible to do string handling in a sane way in C due to the lack of automatic memory management. You can't write a sane (generic, type-safe, fast, no preprocessor nonsense) container library in C. Arbitrary-precision arithmetic is horrible due to the lack of operator overloading.
So sorry, but you're utterly wrong. C is a millstone around the developers' necks for almost every project nowadays.