In the longer term, these sorts of things are governed more by demand than anything else. Sure, some governments might sometimes enact protectionist policies, but if most people in a country think the cars made by their domestic car companies are garbage, they're going to end up with a government that allows cars from other countries in.

If region X happily produces and sells rotten meat, no other region is obligated to trade with them. But region X might choose to import non-rotten meat if they want.

You can absolutely have unidirectional trade, countries produce a different array of goods and these are not bartering deals.

If the US wants to sell cars to the EU, they can. Plenty of countries export cars to the EU just fine. It's not the EU's fault that American car manufacturers make dangerous vehicles. It's also not American car manufacturer's fault that European cities and roads are often smaller and Europeans have less appetite for road deaths. But it is their fault if they want to export to that market without making any effort to design suitable cars for it. American exporters aren't granted a God-given right to inflict American standards in the rest of the world.