The web contains far too many articles about the plus and minus FORMAT WAR and the fallout.
-> As to store bought media, such is pressed and what all DVD players were designed to play.
Recordable media appeared years later so many DVD players didn't have the capability to read one or both recorded media types.
Why is it that commercial DVD'S will play on any format of DVD player but we have DVD-R and DVD+R formats. What are they doing or know that the public doesn't know? Does this make sense?