There are no EU laws. Member states create laws from EU directives. These laws often apply to everyone outside the member country. In practise these laws generally don't matter outside the member state, as it would be nearly impossible to enforce them. But the principle does exist, and the laws sometimes are enforced.

I was using the simplification "EU laws" as a set of laws of the member states (as a citizen of one of those states I know there are no EU laws per se) and what I was asking was how could anyone who has nothing to do with any of the EU states be forced to comply with any of their laws? Why would anyone outside care about them any more than they care about sharia laws enforced in some countries?

The US is the same. Software sales into the US (income from a US source) are subject to US taxes. There's some rules about what exactly constitutes a US source, but from my layman reading it sounds like if you market in the US, you may be required to pay.