If they took money from a single EU citizen / EU-registered card to access their site - then they are trading in the EU and need to offer EU-compliant services. Yes, it's complicated in the modern era, but that's how it works. If you are taking EU money, you need to abide by EU law and - also - pay EU tax.
That's sort of true. A US corporation that has no physical presence in the EU wouldn't have to pay corporation tax in the EU. I don't know if that's the case for the WP, but regardless they do have to collect VAT from EU customers at the customer's local rate, and declare and pay that VAT either in each country individually, or collectively in a single EU country. Which isn't really a tax on the company, it's a tax on EU citizens.