Why would a manual job not be professional?

I have massive respect for the trades people, waitstaff etc, they do much if not all of the actual work on this planet if you discount automation and DIY. A lot of my time has been spent on getting proficient at DIY and every time I look at the end result I know for a fact that even a junior schooled in the art would have done a better job than I did. It still gives me satisfaction, but it also shows me that there is no such thing as a job that isn't worth doing and doing well.

I'm not sure what a 'coffee engineer' is though.