I disagree with being polished. Newer C programs can be robust as well. In fact, I write C programs both for fun and at work and so do a lot of people I know, and these programs still end up being much more robust than I would even expect myself. And when you run them continuously, you will find some bugs in the program but the next bug will appear much later until you don't remember when was the last time a bug caused a failure.
There's something about the robustness you're forced to implement. I never trust scripting languages like that, not mine nor others', as much as solid C. I've seen it way too many times that when a C program is well-written solid code, it keeps on doing what it does and doesn't give surprises. I've had many Python scripts running for years and I always need to fix something little there every year. Maybe something has changed in some library, or I bump into a new failure mode, or something. This rarely happens with a C program once it has "settled".
I worked with PHP for a while and I found it to behave like you describe: I rarely found bugs in code once it reached a stable state. I haven't used Python (I might be the only one), so I can only speculate on whether it's truly more bug-prone than PHP. But one possible reason could be the relatively straightforward behavior of PHP, and C code. (My experience is with non-OO PHP, mainly from hacking Drupal modules, which might make a difference). C and (older) PHP have a small number of data types and few or no hidden behaviors. Neither is OO. I wonder if OO might contribute to long-term instability, because since OO languages are rich in types, they tend to let the language make inferences and allow types to alter the meaning of syntax. For predictable code, you probably want a language that isn't too smart and always gives the same meaning to the same code.
There's something about the robustness you're forced to implement. I never trust scripting languages like that, not mine nor others', as much as solid C. I've seen it way too many times that when a C program is well-written solid code, it keeps on doing what it does and doesn't give surprises. I've had many Python scripts running for years and I always need to fix something little there every year. Maybe something has changed in some library, or I bump into a new failure mode, or something. This rarely happens with a C program once it has "settled".