If the job is for a backend Java developer position, change the list of languages you know from:

    Languages: JavaScript, C#, Python, Java

to:

    Languages: Java, C#, JavaScript, Python

Many times people order their languages by familiarity or preference for working with that technology. Don't make the person looking at the resume have to hunt for the information. If it's last on the list, that may say something about how much you're interested in that job and how likely you are to stay.

> but less clear why a career plumber would tailor resumes for applying to two plumber roles at slightly different companies.

If one company is looking for a plumber to do PEX and another is looking for someone who is experienced with natural gas and black pipe, you might want to make sure that your experience in those two different domains of plumbing are at the front of the experience. They're both plumbers, but the heating and air conditioning company hiring a plumber is looking for different things than the residential new construction plumber.