Someone explain to me why, at the original point of creating a lot, a boundary survey wasn't created or kept on record.

I am wanting to add a few things to my property, and it baffles me why every property (at least in a city) doesn't already have recorded boundary survey measurements on file. I know the work that surveyors do is skilled and precise and hats off to you guys, but dang it's expensive, and it seems like that information should be available somewhere from the start. It's so odd to me that you can buy a house with no one really knowing where the exact boundaries lie, when every other minute detail and 1,000 pages of paperwork is required lol.