I thought it was an Australia thing but yes, $1.50 pipes and $3 fittings are the norm here too. Fortunately, you can 3d print fittings which opens up all sorts of possibilities that don't really make sense for use in plumbing.

https://www.thingiverse.com/thing:2956356

It's probably because the manufacturing process is more complicated.

I bet the pipe is practically continuously extruded from a machine but the fittings also have to be processed and bent into shape before they harden.