[masklinn]

> If my program writes to the standard output, but you choose to redirect the pipe to a different location, is it my program’s responsibility to check what happens to the bytes AFTER the pipe?

The pipe is your standard output. Your very program is created with the pipe as its stdout.

> After all: my program did output everything as expected. The part which fucked up was not part of my program.

But you are wrong, your program did not output everything as expected, and it failed to report that information.