Italians angrily critiquing nontraditional pasta has become something of a meme (see Gordon Ramsay, Binging with Babish, etc's carbonara videos). One thing that people actually do that is agreed upon as both traditional and the correct culinary technique is salting the pasta water.
But not so long ago salt was a valuable commodity! There's no way people would waste 90% of their salt by diluting it in a quart of water and only using half a cup in their sauce, right? So when and where did the tradition come from? Or did salting your water "as salty as the sea" come from literally using seawater?
The specific matter of salting pasta water is ground yet untrod on this sub, and is well worth an answer on its own. If any passing reader can provide a good answer, go right ahead!
However, it does bear noting that while salt was indeed valuable and difficult to make, it's not as expensive as your premise indicates. u/ARandomNameInserted and u/KiwiHellenist both examine salt prices here, while u/wotan_weevil also has a collection of salty threads.