After working both in automotive and at LEGO, I think LEGO is more impressive tolerance wise when it comes to molds, molding and tolerance quality control.

Also to correct you, LEGO has been making most of the parts for decades, some have had changes due to new materials (which you can read upon online) but besides the ones that remained the same (not really), many new system elements got released in the last decades and new I.P tied elements get released on a yearly basis.