Me (14y male from Poland) got my english teacher annoyed/disappointed after saying the word "crap". I'm unsure if this is the right place to ask this question but is saying that word considered bad? I always thought it was pretty mild and not a big deal.
The third one isn't really off-putting because of the word to me and is more about the attitude, even if they said something like "I don't take flak from anyone" I'd have the same reaction.
Indeed, you'd have the same reaction if they said they don't take "shit" from anyone.
You are making my point on all three examples: the direct reference to making a bowel movement is vulgar, there's no situation where "crap" is totally fine and "shit" is not... because crap is only very mildly less vulgar than shit, they are both vulgar references to feces.
I can keep on coming up with examples. The doctor says, "I need a stool sample," vs. the doctor saying, "I need a sample of your crap, please." Substitute shit and it is not particularly more shocking; neither works.
Give it a try: what's an example where "shit" would be shocking, and "crap" would be totally acceptable?
My dude, re-read the comment for a sec. A doctor saying they need a "shit sample" or a "cup of your crap" would both be much more shocking than a stool sample.