Whether gambling is legal or illegal in a given country and /or state is pretty simple to discern. That’s why companies have lawyers. That's why commercials say "not valid in X" and void where prohibited. Why would the law encourage you to be lazy and not to bother looking up the law?
It may be simple to discern for a lawyer, but I wouldn't know where to start with finding reliable info about Hungarian law that's also written in English. I also couldn't be certain I had found everything related to whatever my business is doing. So I'd pretty much have to pay locals to do it for me. I think it's reasonable to assume about 200 locations around the world, and I'll be optimistic and assume the consultations cost an average of $100 a pop, which comes to $20,000. Twenty grand is not a big deal for for an established business, but a few expenses like that can kill a startup.
Also note that I'm thinking in general terms, rather than limiting this to gambling. If this case is successful, it sets a precedent -whether in law or not- of prosecuting international businesses for allowing people to break local laws that the business does not know about.
You could sue a Chinese manufacturer where the product was made, received, or sold. If you’re going to ship an item into country A, how can you expect to be immune from Country A’s laws? How is a digitized ‘product’ different than a physical widget?
As I said before, I would expect them to be held to the laws where they are operating from. Wherever it is they're getting taxed, basically.
Another anology would be banking. There are countries where few details are required by law from the account holder, or/and banks are very protective of customer information (and are backed up by law). The service they provide breaches no international law, nor is it against their local laws. But there are people who take advantage of it to hide their money from scrutiny or taxes, which may be illegal in
their country. Should the bank be prosecutable for not following US laws?
Digital products are very different from physical products. Take books, for example. Grab a physical book without paying for it, and the owner is down one saleable item and has to physically print a replacement. Grab an ebook without paying for it, and the owner has nothing less than they would have if you hadn't (assuming you wouldn't have paid for it in any case). The former is clearly theft, while the latter is closer to counterfeiting, though even that doesn't quite fit. And once you've been a good boy and bought the book, there are still plenty of differences, too: with the physical book, you clearly have ownership over that object (though not the words) and a pretty irrevocable ability to read it, whereas ebooks are generally not sold;
licences to ebooks are sold, and it's not uncommon for those licences to include clauses that allow the seller to revoke them.
The digital world is a new and fundamentally different one. Laws are still catching up, and I suspect they won't until my generation (born in the eighties) starts getting old enough to be making the legislation. Content providers are also in the process of figuring out how to handle it, with the old giants struggling to maintain the status quo, and new startups experimenting and exploring.
EDIT:
EDIT: This isn't just an American concept either. France sued ebay for facilitating the sale of Nazi memorabilia to French citizens as such was illegal under French law.
Was this before or after they got themselves a http://www.ebay.fr/?