Audio tapes (compact cassettes) were invented by Philips, which is a Dutch company. There were a number of incompatible cassette formats in the early 60s (and those old 8-track loops were popular in the US; less so in Europe) but after Philips released the cassette spec. as an open standard the others were squeezed out. US cassette vendors licensed the same general standard as everyone else.
CDs were developed jointly by Philips and Sony, so again, the standard was in place and various US organisations subsequently just sub-licensed it.
There seems to be a bit of a format war brewing up now for the next generation of DVDs (HD DVD versus BluRay) As though betamax versus VHS wasn't bad enough.
