ShowerThoughts

For modern pex plumbing, there are a few different techniques but the easiest for a home owner would be using metal crimp rings and a hand crimp tool which runs about $100. Thats probably the same or less than the hourly rate of a plumber. Plus with modern plumbing measuring doesn't need to be as precise and you can literally just bend the pex to make awkward angles. Even easier than that are push fit fittings. No special tools required but each fitting is more expensive than traditional pex fittings. The biggest benfit of push fit fittings is they can join different types of pipe together, such as copper to pex.

The most important parts of the plumbing code are related to drains, this is to ensure proper drainage and to prevent backflows of sewage into the potable plumbing or accumulation of sewer gases inside the home.

Each industry will have its own jargon, and most industries can be well researched, but as you mentioned when it comes to legal stuff it can be region specific and may extensively rely on previous court rulings. Thats where a good lawyer really makes the difference.

A good plumber and a bad plumber can both replace your sink, the good plumber will likely be cleaner and neater, maybe make it easier to replace again, but both should get the job done. A good programmer could code something to be much more effecient than a bad programmer. A good lawyer versus a bad lawyer could have a much more significant difference in their outcomes.