That is false, at least in the example of online retail. If you sell stuff to someone in another country, online or not, you are bound by the consumer protection laws of that country. So someone in Scandinavia has two years of warranty on a laptop bought on dell.com, vs. one year for an American making the same purchase.

I don't think it makes a difference whether what you are offering is physical or not, your service is bound by the laws in whichever country the exchange takes place. Of course enforcement might be an issue, which is exactly why the Brazilian judge did what he did, when Whatsapp failed to abide by Brazilian law.

Note that I only said "enforce". A country can claim whatever they want within their own borders, but cannot really enforce them across the border.

Even with the laptop warranty case, if some small retailer from Country A shipped a laptop to Scandinavia, but didn't uphold a 2 year warranty, the Scandinavian governments would not be able to force the warranty to be upheld. They can make whatever local judgments they want, but none of them would touch Country A without international agreements in place.