But the industry has different ideas, and they are well funded and influential. We see the results of that influence in international copyright agreements and laws like DCMA.
See for example the Japanese games that have "NO RE-SALE" printed on the back of the box. Japanese publishers pushed pretty hard to make second-hand sales of games illegal. (I don't think that succeeded). It is (or was?) illegal to rent games in Japan.
In the face of this kind of vigorous assertion of rights of IP holders it's can be difficult to stick rigidly to the law.
"Just buy the DVD" doesn't work for the reasons given; just go without is dumb for the reasons you give.
I don't think I'm arguing for the position you think I'm arguing for.
This is definitely not true. Piracy in that region builds up a support infrastructure for piracy that can be used in other regions. It builds social support for piracy, and can spread, as a cultural practice, when people from the afflicted region converse with people from other regions. All of those things can impact sales outside the region.
And there's a simple solution: Make sure that your stuff is available legally everywhere. Because if it's not, you know that it will be pirated.