The point is that it's basically a "global law". Non-EU companies could choose to ignore it, but they would risk losing access to the EU market, which is too big to ignore, and so they comply. A company could forego this or that individual nation, possibly even a big one; but the entirety of the EU market is simply too large to accept the risk.

Similarly, a US company could relocate to Iceland and thumb its nose at the PATRIOT Act and so on, but then "good luck doing any business" in the huge US market. The principle is the same: big markets can impose rules that more or less the entire world ends up following.