Non-dimensional lumber

Carpentry is fascinating.  Well, I'm fascinated, even if you aren't.  And if you're reading this, maybe you will get fascinated too.

Start with the lumber, so-called "dimensional lumber."  I guess they call it that because it comes in standard dimensions.  Yeah, right.

Who came up with the idea that a standard 2 x 4 should be 1.5 x 3.5?  And a standard 4 x 4 should be 3.5 x 3.5?  And so forth ... you get the idea.  Who?  Who! would invent such a system?

Okay, I can adapt.  I can translate all the 2 x 4s into 1.5 x 3.5s.  I have a Ph.D. 

But, then there is this other little kicker:  THEY AREN'T!  They aren't all the same size!  WHO???!!! WOULD INVENT SUCH A SYSTEM?  Clearly, they were not women.

The result is that you spend all this time making sure that your plans are accurate, that your measurements are right (measure twice ... or 3 or 4 times; cut once), that your corners are square, that your saw's fence is square, etc. etc. Then, you apply it all to lumber that has a degree of randonmess usually reserved for econometric equations.  I have not seen a single piece of carpentry advice that tells you anything about an error term.  But now you know.  The dirty little secret is out.

Can't we solve this problem?  It is the 21st century. Most machines are (or can be) controlled by computers. Don't you think it would be possible to cut two boards into equivalent sizes?  I wonder what dimensional lumber is like in countries that use the metric system?  Who regulates this stuff?