A second reason is simply that the US as a big homogeneous market is a nice one to tackle for European companies as well. And often that means having a (big) presence in the US. The EU is basically many markets unified by really complex rules, bureaucracy, etc. There is free traffic of people but companies have a harder time dealing with local variations in legislation, hurdles for billing and taxation (e.g. VAT), banking, bureaucracy, etc.
Seems like this would be a really cool idea for a startup (that might already exist?). Stripe stripe/shopify for EU?
