I am a programmer, and I still can't fix free software I don't like. It's the same reason that people use off-the-shelf software in the first place -- DIY just takes too much time.
Well, you know... it's open source and it's free. You can fix it if you want. But no one does, they just complain.
And if they do fix it, they don't commit the changes to get them integrated, so they can't upgrade anymore. shrug
I can't engineer a car - does that mean I shouldn't get mad when my airbags fail to deploy? I can't cook well - does that mean I shouldn't be disappointed by a substandard meal at a restaurant?
A better analogy would be going to a food shelter, getting a free meal, then complaining that they didn't put enough salt on it, when the salt is right there on the table in front of you.
After a certain point, one just stops bothering.