The end user doesn't directly care, but if you solve their problem in a hacky unmaintainable way, they'll care when it takes you days to do what should take hours, weeks to do what should take days.
So writing my app in <your preferred language> automatically makes it elegant?
No. I didn't say that. The language you write in doesn't matter nearly as much as your attitude about writing the software. If you don't design for maintainability and readability, then modifying the code later will take much longer.
I'm not a coder, and I wouldn't be building stuff today if I didn't have PHP. I think a lot of people probably feel that way.
Programma hatas gon hate.
I may not care, but I end up knowing every time I see one of those PHP/MySQL error traces in a website. Apparently one of their problems isn't proper exception handling.
So writing my app in <your preferred language> automatically ensures my database will be up and all exceptions are handled correctly?
No, it does, however, ensure that my errors don't randomly get dumped on the page, and that instead an exception is raised and a proper 500 page can be returned.