How far apart are Louisiana and California? How far apart are Romania and Bulgaria? Yet, the two USA states share the same language (at least on official level), the same currency and the same "american" culture. Neither of these is true for BG and RO. And we are neighbours, mind that. As an added "benefit", we have separate electronic payment providers (+ most of the American ones). We use Visa and PayPal when we need to pay between countries. Until recently we didn't even have a common banking accounts system. Now we have IBAN and it's a lot better. We also don't have a common postal office. If I send a parcel from one neighbouring town of BG, to a town across Danube, it becomes an international delivery, and 5 years ago used to have to pass through the customs office.
As someone else mentioned, it's much better to sell from Romania (and Bulgaria for that matter) directly to the USA, instead of trying to enter the neighbour market.
And now surprise, we are always considered about the same thing by EU officials. We were accepted to the EU together, we must join the Schengen area together, we must adopt the Euro together... It's crazy :).
So, no, if we cave to compare to CA and LA, nope, they are a lot more similar.